N-optionally substituted aryl-2-oligomer-3-alkoxypropionamides

ABSTRACT

The invention relates to (among other things) N-optionally substituted aryl-2-oligomer-3-alkoxypropionamides and compositions comprising the same. A compound of the invention, when administered by any of a number of administration routes, exhibits one or more advantages over corresponding compounds lacking the oligomer.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patent application Ser. No. 15/445,381, filed Feb. 28, 2017, which is a continuation application of U.S. patent application Ser. No. 14/951,105, filed Nov. 24, 2015, now U.S. Pat. No. 9,616,136, which is a continuation application of U.S. patent application Ser. No. 13/879,603, filed Apr. 8, 2014, now U.S. Pat. No. 9,226,971, which is a 35 U.S.C. § 371 application of International Application No. PCT/US2011/056391, filed Oct. 14, 2011, designating the United States, which claims the benefit of priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application No. 61/393,699, filed Oct. 15, 2010, the disclosures of which are incorporated herein by reference in their entireties.

FIELD OF THE INVENTION

This invention comprises (among other things) N-optionally substituted aryl-2-oligomer-3-alkoxypropionamides. The N-optionally substituted aryl-2-oligomer-3-alkoxypropionamides described herein relate to and/or have application(s) in (among others) the fields of drug discovery, pharmacotherapy, physiology, organic chemistry and polymer chemistry.

BACKGROUND OF THE INVENTION

Epilepsy is a common chronic neurological disorder characterized by recurrent unprovoked seizures. These seizures are transient signs and/or symptoms of abnormal, excessive or synchronous neuronal activity in the brain. About 50 million people worldwide have epilepsy, with almost 90% of these people residing in developing countries. Epilepsy is more likely to occur in young children or people over the age of 65 years; however, it can occur at any age. Epilepsy is usually controlled, but not cured, with pharmacotherapy, although surgery may be indicated in exceptional cases. Despite the reliance on pharmacotherapy as the primary approach in controlling the disease, over 30% of people with epilepsy do not have seizure control even with the best available medications. Not all epilepsy syndromes are life-long; some forms are confined to particular stages of childhood. Epilepsy should not be understood as a single disorder, but rather as a group of syndromes with vastly divergent symptoms, but all involving episodic abnormal electrical activity in the brain.

Seizure types are organized firstly according to whether the source of the seizure within the brain is localized (partial or focal onset seizures) or distributed (generalized seizures). Partial seizures are further divided on the extent to which consciousness is affected. If it is unaffected, then it is a simple partial seizure; otherwise it is a complex partial (psychomotor) seizure. A partial seizure may spread within the brain—a process known as secondary generalization. Generalized seizures are divided according to the effect on the body, but all involve loss of consciousness. These include absence (petit mal), myoclonic, clonic, tonic, tonic-clonic (grand mal) and atonic seizures.

There are over 40 different types of epileptic conditions, including: absence seizures, atonic seizures, benign Rolandic epilepsy, childhood absence, clonic seizures, complex partial seizures, frontal lobe epilepsy, febrile seizures, infantile spasms, juvenile myoclonic epilepsy, juvenile absence epilepsy, Lennox-Gastaut syndrome, Landau-Kleffner syndrome, myoclonic seizures, mitochondrial disorders, progressive myoclonic epilepsies, psychogenic seizures, reflex epilepsy, Rasmussen's syndrome, simple partial seizures, secondarily generalized seizures, temporal lobe epilepsy, toni-clonic seizures, tonic seizures, psychomotor seizures, limbic epilepsy, partial-onset seizures, generalized-onset seizures, status epilepticus, abdominal epilepsy, akinetic seizures, auto-nomic seizures, massive bilateral myoclonus, catamenial epilepsy, drop seizures, emotional seizures, focal seizures, gelastic seizures, Jacksonian march, Lafora disease, motor seizures, multifocal seizures, neonatal seizures, nocturnal seizures, photosensitive seizure, pseudo seizures, sensory seizures, subtle seizures, Sylvan seizures, withdrawal seizures, and visual reflex seizures, among others.

Anticonvulsants are generally prescribed for the treatment of individuals suffering from or prone to epilepsy. The 3-alkoxypropionamides represent one such class of compounds. The 3-alkoxypropionamides are also used in the treatment of individuals suffering from or prone to neuropathic pain. Treatment of individuals with these compounds, however, is associated with many side effects, including: vertigo; diplopia; blurred vision; nausea; vomiting; dizziness; ataxia; and tremor.

Therefore, pharmacotherapy with such therapeutic 3-alkoxypropionamides would be improved if these and/or other adverse or side effects associated with their use could be decreased or if their pharmacology could otherwise be improved for this and/or for other indications. Thus, there is a large unmet need for developing novel 3-alkoxypropionamides.

The present invention seeks to address these and other needs in the art.

SUMMARY OF THE INVENTION

In one or more embodiments of the invention, N-optionally substituted aryl-2-oligomer-3-alkoxypropionamides are provided.

In one or more embodiments of the invention a compound is provided, the compound comprising a 3-alkoxypropionamide residue covalently attached via a stable or degradable linkage to a water-soluble, non-peptidic oligomer.

The “3-alkoxypropionamide residue” is a compound having a structure of a therapeutically active 3-alkoxypropionamide that is altered by the presence of one or more bonds, which bonds serve to attach (either directly or indirectly) one or more water-soluble, non-peptidic oligomers.

Exemplary compounds of the invention include those having the following structure:

wherein:

Ar is aryl, optionally substituted (e.g., optionally substituted with halo);

R¹ is lower alkyl;

the dotted line (“---”) represents a covalent bond, optionally oriented to provide the R enantiomer;

X¹ is a spacer moiety;

POLY¹ is a water-soluble, non-peptidic oligomer.

In this regard, any 3-alkoxypropionamide having anti-epileptic and/or analgesic activity can be used as the 3-alkoxypropionamide from which the 3-alkoxypropionamide residue is obtained. Exemplary 3-alkoxypropionamides have a structure encompassed by Formula I:

wherein:

Ar is aryl, optionally substituted with halo; and

R¹ is lower alkyl.

An exemplary 3-alkoxypropionamide for use in the current invention is lacosamide.

In one or more embodiments of the invention, N-optionally substituted aryl-2-oligomer-3-alkoxypropionamides are provided.

In one or more embodiments of the invention, a composition is provided, the composition comprising an N-optionally substituted aryl-2-oligomer-3-alkoxypropionamide, and optionally, a pharmaceutically acceptable excipient.

In one or more embodiments of the invention, a compound is provided, the compound comprising a 3-alkoxypropionamide residue covalently attached via a stable or degradable linkage to a water-soluble, non-peptidic oligomer.

In one or more embodiments of the invention, a composition is provided, the composition comprising a compound comprising a 3-alkoxypropionamide residue covalently attached via a stable or degradable linkage to a water-soluble, non-peptidic oligomer, and optionally, a pharmaceutically acceptable excipient.

In one or more embodiments of the invention, a dosage form is provided, the dosage form comprising a compound as described herein, wherein the compound is present in a dosage form.

In one or more embodiments of the invention, a method is provided, the method comprising covalently attaching a water-soluble, non-peptidic oligomer to a 3-alkoxypropionamide.

In one or more embodiments of the invention, a method is provided, the method comprising administering a compound as described herein to a mammal in need thereof.

Additional embodiments of the present conjugates, compositions, methods, and the like will be apparent from the following description, examples, and claims. As can be appreciated from the foregoing and following description, each and every feature described herein, and each and every combination of two or more of such features, is included within the scope of the present disclosure provided that the features included in such a combination are not mutually inconsistent. In addition, any feature or combination of features may be specifically excluded from any embodiment of the present invention. Additional aspects and advantages of the present invention are set forth in the following description and claims.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is the voltage protocol for the hNav1.8 test procedure described in further detail in Example 2.

FIG. 2 is a graph of the Phase 1 and Phase 2 measurements of flinches induced by formalin administration as further described in Example 4.

DETAILED DESCRIPTION OF THE INVENTION

As used in this specification, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.

In describing and claiming the present invention, the following terminology will be used in accordance with the definitions described below.

“Water soluble, non-peptidic oligomer” indicates an oligomer that is at least 35% (by weight) soluble, preferably greater than 70% (by weight), and more preferably greater than 95% (by weight) soluble, in water at room temperature. Typically, an unfiltered aqueous preparation of a “water-soluble” oligomer transmits at least 75%, more preferably at least 95%, of the amount of light transmitted by the same solution after filtering. It is most preferred, however, that the water-soluble oligomer is at least 95% (by weight) soluble in water or completely soluble in water. With respect to being “non-peptidic,” an oligomer is non-peptidic when it has less than 35% (by weight) of amino acid residues.

The terms “monomer,” “monomeric subunit” and “monomeric unit” are used interchangeably herein and refer to one of the basic structural units of a polymer or oligomer. In the case of a homo-oligomer, a single repeating structural unit forms the oligomer. In the case of a co-oligomer, two or more structural units are repeated—either in a pattern or randomly—to form the oligomer. Preferred oligomers used in connection with present the invention are homo-oligomers. The water-soluble, non-peptidic oligomer comprises one or more monomers serially attached to form a chain of monomers. The oligomer can be formed from a single monomer type (i.e., is homo-oligomeric) or two or three monomer types (i.e., is co-oligomeric).

An “oligomer” is a molecule possessing from about 1 to about 30 monomers. Specific oligomers for use in the invention include those having a variety of geometries such as linear, branched, or forked, to be described in greater detail below.

“PEG” or “polyethylene glycol,” as used herein, is meant to encompass any water-soluble poly(ethylene oxide). Unless otherwise indicated, a “PEG oligomer” or an oligoethylene glycol is one in which substantially all (preferably all) monomeric subunits are ethylene oxide subunits, though, the oligomer may contain distinct end capping moieties or functional groups, e.g., for conjugation. PEG oligomers for use in the present invention will comprise one of the two following structures: “—(CH₂CH₂O)_(n)—” or “—(CH₂CH₂O)_(n-1)CH₂CH₂—,” depending upon whether or not the terminal oxygen(s) has been displaced, e.g., during a synthetic transformation. As stated above, for the PEG oligomers, the variable (n) ranges from about 1 to 30, and the terminal groups and architecture of the overall PEG can vary. When PEG further comprises a functional group, A, for linking to, e.g., a small molecule drug, the functional group when covalently attached to a PEG oligomer does not result in formation of (i) an oxygen-oxygen bond (—O—, a peroxide linkage), or (ii) a nitrogen-oxygen bond (N—O, O—N).

The terms “end-capped” or “terminally capped” are interchangeably used herein to refer to a terminal or endpoint of a polymer having an end-capping moiety. Typically, although not necessarily, the end-capping moiety comprises a hydroxy or C₁₋₂₀ alkoxy group. Thus, examples of end-capping moieties include alkoxy (e.g., methoxy, ethoxy and benzyloxy), as well as aryl, heteroaryl, cyclo, heterocyclo, and the like. In addition, saturated, unsaturated, substituted and unsubstituted forms of each of the foregoing are envisioned. Moreover, the end-capping group can also be a silane. The end-capping group can also advantageously comprise a detectable label. When the oligomer has an end-capping group comprising a detectable label, the amount or location of the oligomer and/or the moiety (e.g., active agent) of interest to which the oligomer is coupled, can be determined by using a suitable detector. Such labels include, without limitation, fluorescers, chemiluminescers, moieties used in enzyme labeling, colorimetric moieties (e.g., dyes), metal ions, radioactive moieties, and the like. Suitable detectors include photometers, films, spectrometers, and the like. In addition, the end-capping group may contain a targeting moiety.

The term “targeting moiety” is used herein to refer to a molecular structure that helps the compounds of the invention to localize to a targeting area, e.g., help enter a cell, or bind a receptor. Preferably, the targeting moiety comprises a vitamin, antibody, antigen, receptor, DNA, RNA, sialyl Lewis X antigen, hyaluronic acid, sugars, cell-specific lectins, steroid or steroid derivative, RGD peptide, ligand for a cell surface receptor, serum component, or combinatorial molecule directed against various intra- or extracellular receptors. The targeting moiety may also comprise a lipid or a phospholipid. Exemplary phospholipids include, without limitation, phosphatidylcholines, phosphatidylserine, phosphatidylinositol, phosphatidylglycerol, and phosphatidylethanolamine. These lipids may be in the form of micelles or liposomes and the like. The targeting moiety may further comprise a detectable label or alternately a detectable label may serve as a targeting moiety.

“Branched,” in reference to the geometry or overall structure of an oligomer, refers to an oligomer having two or more polymer “arms” extending from a branch point.

“Forked,” in reference to the geometry or overall structure of an oligomer, refers to an oligomer having two or more functional groups (typically through one or more atoms) extending from a branch point.

A “branch point” refers to a bifurcation point comprising one or more atoms at which an oligomer branches or forks from a linear structure into one or more additional arms.

The terms “reactive” and “activated” refer to a functional group that reacts readily or at a practical rate under conventional conditions of organic synthesis. This is in contrast to those groups that either do not react or require strong catalysts or impractical reaction conditions in order to react (i.e., a “nonreactive” or “inert” group).

“Not readily reactive,” with reference to a functional group present on a molecule in a reaction mixture, indicates that the group remains largely intact under conditions that are effective to produce a desired reaction in the reaction mixture.

A “protecting group” is a moiety that prevents or blocks reaction of a particular chemically reactive functional group in a molecule under certain reaction conditions. The protecting group may vary depending upon the type of chemically reactive group being protected as well as the reaction conditions to be employed and the presence of additional reactive or protecting groups in the molecule. Functional groups which may be protected include, by way of example, carboxylic acid groups, amino groups, hydroxyl groups, thiol groups, carbonyl groups and the like. Representative protecting groups for carboxylic acids include esters (such as a p-methoxybenzyl ester), amides and hydrazides; for amino groups, carbamates (such as tert-butoxycarbonyl) and amides; for hydroxyl groups, ethers and esters; for thiol groups, thioethers and thioesters; for carbonyl groups, acetals and ketals; and the like. Such protecting groups are well-known to those skilled in the art and are described, for example, in T. W. Greene and G. M. Wuts, Protecting Groups in Organic Synthesis, Third Edition, Wiley, New York, 1999, and references cited therein.

A functional group in “protected form” refers to a functional group bearing a protecting group. As used herein, the term “functional group” or any synonym thereof encompasses protected forms thereof.

A “physiologically cleavable” or “hydrolyzable” or “degradable” bond is releasable linkage that reacts with water (i.e., is hydrolyzed) under physiological conditions. The tendency of a bond to hydrolyze in water may depend not only on the general type of linkage connecting two central atoms but also on the substituents attached to these central atoms. Appropriate hydrolytically unstable or weak linkages include but are not limited to carboxylate ester, phosphate ester, anhydrides, acetals, ketals, acyloxyalkyl ether, imines, orthoesters, peptides, oligonucleotides, thioesters, and carbonates.

An “enzymatically degradable linkage” means a linkage that is subject to degradation by one or more enzymes.

A “stable” linkage or bond refers to a chemical bond that is substantially stable in water, that is to say, does not undergo hydrolysis under physiological conditions to any appreciable extent over an extended period of time. Examples of hydrolytically stable linkages include but are not limited to the following: carbon-carbon bonds (e.g., in aliphatic chains), ethers, amides, urethanes, amines, and the like. Generally, a stable linkage is one that exhibits a rate of hydrolysis of less than about 1-2% per day under physiological conditions. Hydrolysis rates of representative chemical bonds can be found in most standard chemistry textbooks.

“Substantially” or “essentially” means nearly totally or completely, for instance, 95% or greater, more preferably 97% or greater, still more preferably 98% or greater, even more preferably 99% or greater, yet still more preferably 99.9% or greater, with 99.99% or greater being most preferred of some given quantity.

“Monodisperse” refers to an oligomer composition wherein substantially all of the oligomers in the composition have a well-defined, single molecular weight and defined number of monomers, as determined by chromatography or mass spectrometry. Monodisperse oligomer compositions are in one sense pure, that is, substantially having a single and definable number (as a whole number) of monomers rather than a large distribution. A monodisperse oligomer composition possesses a MW/Mn value of 1.0005 or less, and more preferably, a MW/Mn value of 1.0000. By extension, a composition comprised of monodisperse conjugates means that substantially all oligomers within all compounds in the composition have a single and definable number (as a whole number) of monomers rather than a large distribution and would possess a MW/Mn value of 1.0005, and more preferably, a MW/Mn value of 1.0000 if the oligomer were not attached to the therapeutic moiety. A composition comprised of monodisperse conjugates may, for example, include one or more nonconjugate substances such as solvents, reagents, excipients, and so forth.

“Bimodal,” in reference to an oligomer composition, refers to an oligomer composition wherein substantially all oligomers in the composition have one of two definable and different numbers (as whole numbers) of monomers rather than a large distribution, and whose distribution of molecular weights, when plotted as a number fraction versus molecular weight, appears as two separate identifiable peaks. Preferably, for a bimodal oligomer composition as described herein, each peak is generally symmetric about its mean, although the size of the two peaks may differ. Ideally, the polydispersity index of each peak in the bimodal distribution, Mw/Mn, is 1.01 or less, more preferably 1.001 or less, and even more preferably 1.0005 or less, and most preferably a MW/Mn value of 1.0000. By extension, a composition comprised of bimodal conjugates means that substantially all oligomers of all conjugates in the composition have one of two definable and different numbers (as whole numbers) of monomers rather than a large distribution and would possess a MW/Mn value of 1.01 or less, more preferably 1.001 or less and even more preferably 1.0005 or less, and most preferably a MW/Mn value of 1.0000 if the oligomer were not attached to the therapeutic moiety. A composition comprised of bimodal conjugates may, for example, include one or more nonconjugate substances such as solvents, reagents, excipients, and so forth.

A “3-alkoxypropionamide” is broadly used herein to refer to an organic, inorganic, or organometallic compound having a molecular weight of less than about 1000 Daltons (more preferably less than about 500 Daltons and most preferably having less than about 300 Daltons) and having some degree of activity as an anti-epileptic and/or analgesic. Assays known to those of ordinary skill in the art can be used to determine whether a given 3-alkoxypropionamide (as well as a compound provided herein) has activity as an anti-epileptic and/or analgesic.

A “biological membrane” is any membrane made of cells or tissues that serves as a barrier to at least some foreign entities or otherwise undesirable materials. As used herein a “biological membrane” includes those membranes that are associated with physiological protective barriers including, for example: the blood-brain barrier (BBB); the blood-cerebrospinal fluid barrier; the blood-placental barrier; the blood-milk barrier; the blood-testes barrier; and mucosal barriers including the vaginal mucosa, urethral mucosa, anal mucosa, buccal mucosa, sublingual mucosa, and rectal mucosa. Unless the context clearly dictates otherwise, the term “biological membrane” does not include those membranes associated with the middle gastro-intestinal tract (e.g., stomach and small intestines).

A “biological membrane crossing rate,” provides a measure of a compound's ability to cross a biological membrane, such as the blood-brain barrier (“BBB”). A variety of methods may be used to assess transport of a molecule across any given biological membrane. Methods to assess the biological membrane crossing rate associated with any given biological barrier (e.g., the blood-cerebrospinal fluid barrier, the blood-placental barrier, the blood-milk barrier, the intestinal barrier, and so forth), are known, described herein and/or in the relevant literature, and/or may be determined by one of ordinary skill in the art.

A “reduced rate of metabolism” refers to a measurable reduction in the rate of metabolism of a water-soluble oligomer-small molecule drug conjugate as compared to the rate of metabolism of the small molecule drug not attached to the water-soluble oligomer (i.e., the small molecule drug itself) or a reference standard material. In the special case of “reduced first pass rate of metabolism,” the same “reduced rate of metabolism” is required except that the small molecule drug (or reference standard material) and the corresponding conjugate are administered orally. Orally administered drugs are absorbed from the gastro-intestinal tract into the portal circulation and may pass through the liver prior to reaching the systemic circulation. Because the liver is the primary site of drug metabolism or biotransformation, a substantial amount of drug may be metabolized before it ever reaches the systemic circulation. The degree of first pass metabolism, and thus, any reduction thereof, may be measured by a number of different approaches. For instance, animal blood samples may be collected at timed intervals and the plasma or serum analyzed by liquid chromatography/mass spectrometry for metabolite levels. Other techniques for measuring a “reduced rate of metabolism” associated with the first pass metabolism and other metabolic processes are known, described herein and/or in the relevant literature, and/or may be determined by one of ordinary skill in the art. Preferably, a compound of the invention may provide a reduced rate of metabolism [relative to a compound lacking a water-soluble, non-peptidic oligomers) satisfying at least one of the following values: at least about 30%; at least about 40%; at least about 50%; at least about 60%; at least about 70%; at least about 80%; and at least about 90%. A compound (such as a small molecule drug or conjugate thereof) that is “orally bioavailable” is one that preferably possesses a bioavailability when administered orally of greater than 25%, and preferably greater than 70%, where a compound's bioavailability is the fraction of administered drug that reaches the systemic circulation in unmetabolized form.

“Alkyl” refers to a hydrocarbon chain, ranging from about 1 to 20 atoms in length. Such hydrocarbon chains are preferably but not necessarily saturated and may be branched or straight chain. Exemplary alkyl groups include methyl, ethyl, propyl, butyl, pentyl, 2-methylbutyl, 2-ethylpropyl, 3-methylpentyl, and the like. As used herein, “alkyl” includes cycloalkyl when three or more carbon atoms are referenced. An “alkenyl” group is an alkyl of 2 to 20 carbon atoms with at least one carbon-carbon double bond.

The terms “substituted alkyl” or “substituted C_(q-r) alkyl” where q and r are integers identifying the range of carbon atoms contained in the alkyl group, denotes the above alkyl groups that are substituted by one, two or three halo (e.g., F, Cl, Br, I), trifluoromethyl, hydroxy, C₁₋₇ alkyl (e.g., methyl, ethyl, n-propyl, isopropyl, butyl, t-butyl, and so forth), C₁₋₇ alkoxy, C₁₋₇ acyloxy, C₃₋₇ heterocyclic, amino, phenoxy, nitro, carboxy, acyl, cyano. The substituted alkyl groups may be substituted once, twice or three times with the same or with different substituents.

“Lower alkyl” refers to an alkyl group containing from 1 to 6 carbon atoms, and may be straight chain or branched, as exemplified by methyl, ethyl, n-butyl, i-butyl, t-butyl. “Lower alkenyl” refers to a lower alkyl group of 2 to 6 carbon atoms having at least one carbon-carbon double bond.

“Non-interfering substituents” are those groups that, when present in a molecule, are typically non-reactive with other functional groups contained within the molecule.

“Alkoxy” refers to an —O—R group, wherein R is alkyl or substituted alkyl, preferably C₁-C₂₀ alkyl (e.g., methoxy, ethoxy, propyloxy, etc.), preferably C₁-C₇.

“Pharmaceutically acceptable excipient” or “pharmaceutically acceptable carrier” refers to a component that may be included in the compositions of the invention causes no significant adverse toxicological effects to a patient.

The term “aryl” means an aromatic-containing group having up to 14 carbon atoms. Aryl groups include benzyl, phenyl, naphthyl, biphenyl, phenanthrenyl, naphthalenyl, and the like. “Substituted phenyl,” “substituted benzyl” and “substituted aryl” denote a phenyl group, benzyl group and aryl group, respectively, substituted with one, two, three, four or five (e.g., 1-2, 1-3 or 1-4 substituents) chosen from halo (e.g., F, Cl, Br, I), hydroxy, cyano, nitro, alkyl (e.g., C₁₋₆ alkyl), alkoxy (e.g., C₁₋₆ alkoxy), benzyloxy, carboxy, aryl, and so forth.

Chemical moieties are defined and referred to throughout primarily as univalent chemical moieties (e.g., alkyl, aryl, etc.). Nevertheless, such terms are also used to convey corresponding multivalent moieties under the appropriate structural circumstances clear to those skilled in the art. For example, while an “alkyl” moiety generally refers to a monovalent radical (e.g., CH₃—CH₂—), in certain circumstances a bivalent linking moiety can be “alkyl,” in which case those skilled in the art will understand the alkyl to be a divalent radical (e.g., —CH₂—CH₂—), which is equivalent to the term “alkylene.” (Similarly, in circumstances in which a divalent moiety is required and is stated as being “aryl,” those skilled in the art will understand that the term “aryl” refers to the corresponding multivalent moiety, arylene). All atoms are understood to have their normal number of valences for bond formation (i.e., 1 for H, 4 for carbon, 3 for N, 2 for O, and 2, 4, or 6 for S, depending on the oxidation state of the S).

“Pharmacologically effective amount,” “physiologically effective amount,” and “therapeutically effective amount” are used interchangeably herein to mean the amount of the compound of the invention present in a composition that is needed to provide a desired level of the compound (or desired metabolite thereof) in the bloodstream or in the target tissue. The precise amount may depend upon numerous factors, e.g., the particular active agent, the components and physical characteristics of the composition, intended patient population, patient considerations, and may readily be determined by one skilled in the art, based upon the information provided herein and available in the relevant literature.

A “difunctional” oligomer is an oligomer having two functional groups contained therein, typically at its termini. When the functional groups are the same, the oligomer is said to be homodifunctional. When the functional groups are different, the oligomer is said to be heterodifunctional.

A basic reactant or an acidic reactant described herein include neutral, charged, and any corresponding salt forms thereof.

The term “patient,” refers to a living organism suffering from or prone to a condition that can be prevented or treated by administration of a compound of the invention as described herein, and includes both humans and animals.

“Optional” or “optionally” means that the subsequently described circumstance may but need not necessarily occur, so that the description includes instances where the circumstance occurs and instances where it does not.

As indicated above, the present invention is directed to (among other things) N-optionally substituted aryl-2-oligomer-3-alkoxypropionamides. By way of “N-optionally substituted aryl-2-oligomer-3-alkoxypropionamides” are meant propionamides, wherein: the nitrogen of the propionamide is N-substituted with an aryl group (which aryl group is optionally substituted); the “2-position” carbon of the propionamide has attached to it (optionally arranged so as to provide the R-enantiomer), directly or via a spacer moiety, a water-soluble, non-peptidic oligomer; and the “3-position” carbon of the propronamide has attached to it an alkoxy group. These features of N-optionally substituted aryl-2-oligomer-3-alkoxypropionamides are schematically provided below:

Exemplary N-optionally substituted aryl-2-oligomer-3-alkoxypropionamides of the invention include those having the following structure:

wherein:

Ar is aryl, optionally substituted with halo;

R¹ is lower alkyl;

the dotted line (“---”) represents a covalent bond, optionally oriented to provide the R enantiomer;

X¹ is a spacer moiety; and

POLY¹ is a water-soluble, non-peptidic oligomer.

Further, exemplary compounds of Formula Ia-C include those having the following structure:

wherein:

Ar is aryl, optionally substituted with halo;

R¹ is lower alkyl;

X¹ is a spacer moiety; and

POLY¹ is a water-soluble, non-peptidic oligomer.

Still further exemplary compounds of Formula Ia-C include those having the following structure:

wherein:

Ar is aryl, optionally substituted with halo;

R¹ is lower alkyl;

X¹ is a spacer moiety; and

POLY¹ is a water-soluble, non-peptidic oligomer.

Other compounds of interest that may be useful as (among other things) probes to determine binding affinity include those encompassed by the following structure:

wherein:

Ar is aryl, optionally substituted with halo;

the dotted line (“---”) represents a covalent bond, optionally oriented to provide the R enantiomer;

X¹ is a spacer moiety (preferably —O—); and

POLY¹ is a water-soluble, non-peptidic oligomer.

Still exemplary compounds of interest that may be useful as (among other things) probes to determine binding affinity include those encompassed by the following formula:

wherein:

Ar—X¹-POLY¹ is aryl substituted with —X¹—POLY¹ and further optionally substituted with halo, wherein X¹ is a spacer moiety (preferably —O—, —S— or —NH—) and POLY¹ is a water-soluble, non-peptidic oligomer;

the dotted line (“---”) represents a covalent bond, optionally oriented to provide the R enantiomer; and

R¹ is lower alkyl.

As indicated above, the present invention is directed to (among other things) a compound comprising a 3-alkoxypropionamide residue covalently attached via a stable or degradable linkage to a water-soluble, non-peptidic oligomer.

The “3-alkoxypropionamide residue” is a compound having a structure of a 3-alkoxypropionamide that is altered by the presence of one or more bonds, which bonds serve to attach (either directly or indirectly) one or more water-soluble, non-peptidic oligomers. Exemplary 3-alkoxypropionamides have a structure encompassed by Formula I:

wherein:

Ar is aryl, optionally substituted with halo; and

R¹ is lower alkyl.

As previously indicated, the nitrogen of the propionamide within the N-optionally substituted aryl-2-oligomer-3-alkoxypropionamide is N-substituted with an aryl group. Preferably, the aryl group is a benzyl group, although the invention is not limited in this regard. Further, the aryl group (e.g., a benzyl group) is optionally substituted with, for example, one or more lower alkyls and/or halo atoms. When the aryl group is substituted, it is preferred that the aryl group is halo-substituted.

In one or more embodiments of the invention, a compound is provided, the compound comprising a 3-alkoxypropionamide residue covalently attached via a stable or degradable linkage to a water-soluble, non-peptidic oligomer, wherein the 3-alkoxypropionamide residue (in a form in which the water-soluble, non-peptidic oligomer is not present) corresponds to lacosamide [i.e., (R)—N-benzyl-2-acetamido-3-methoxy propionamide]. The following list provides the chemical structures of these and other exemplary 3-alkoxypropionamide moieties:

-   (R)—N-benzyl-2-acetamido-3-methoxy propionamide (lacosamide);

-   (R)—N-benzyl-2-acetamido-3-ethoxy propionamide;

-   (R)—N-(3-fluorobenzyl)-2-acetamido-3-methoxy propionamide; and

-   (R)—N-(4-fluorobenzyl)-2-acetamido-3-methoxy propionamide.

In some instances, a 3-alkoxypropionamide that is useful as a starting material or intermediate in synthesizing the compounds of the invention can be obtained from commercial sources. In addition, 3-alkoxypropionamides can be obtained through chemical synthesis. Further examples of 3-alkoxypropionamides, as well as synthetic approaches for preparing 3-alkoxypropionamides, are described in the literature and in, for example, U.S. Reissue Pat. No. RE 38,551 and U.S. Pat. No. 5,654,301. Each of these (and other) 3-alkoxypropionamides can be covalently attached (either directly or through one or more atoms) to a water-soluble, non-peptidic oligomer following the techniques and approaches described herein.

With respect to the water-soluble, non-peptidic oligomer, use of discrete oligomers (e.g., from a monodisperse or bimodal composition of oligomers, in contrast to relatively impure compositions) to form oligomer-containing compounds are preferred. For instance, a compound of the invention, when administered by any of a number of suitable administration routes, such as parenteral, oral, transdermal, buccal, pulmonary, or nasal, exhibits reduced penetration across the blood-brain barrier. It is preferred that the compounds of the invention exhibit slowed, minimal or effectively no crossing of the blood-brain barrier, while still crossing the gastro-intestinal (GI) walls and into the systemic circulation when oral delivery is intended. Moreover, the compounds of the invention maintain a degree of bioactivity as well as bioavailability in comparison to the bioactivity and bioavailability of the compound free of all oligomers.

With respect to the blood-brain barrier (“BBB”), this barrier restricts the transport of drugs from the blood to the brain. This barrier consists of a continuous layer of unique endothelial cells joined by tight junctions. The cerebral capillaries, which comprise more than 95% of the total surface area of the BBB, represent the principal route for the entry of most solutes and drugs into the central nervous system.

For compounds whose degree of blood-brain barrier crossing ability is not readily known, such ability may be determined using a suitable animal model such as an in situ rat brain perfusion (“RBP”) model as described herein. Briefly, the RBP technique involves cannulation of the carotid artery followed by perfusion with a compound solution under controlled conditions, followed by a wash out phase to remove compound remaining in the vascular space. (Such analyses may be conducted, for example, by contract research organizations such as Absorption Systems, Exton, Pa.). In one example of the RBP model, a cannula is placed in the left carotid artery and the side branches are tied off. A physiologic buffer containing the analyte (typically but not necessarily at a 5 micromolar concentration level) is perfused at a flow rate of about 10 mL/minute in a single pass perfusion experiment. After 30 seconds, the perfusion is stopped and the brain vascular contents are washed out with compound-free buffer for an additional 30 seconds. The brain tissue is then removed and analyzed for compound concentrations via liquid chromatography with tandem mass spectrometry detection (LC/MS/MS). Alternatively, blood-brain barrier permeability can be estimated based upon a calculation of the compound's molecular polar surface area (“PSA”), which is defined as the sum of surface contributions of polar atoms (usually oxygens, nitrogens and attached hydrogens) in a molecule. The PSA has been shown to correlate with compound transport properties such as blood-brain barrier transport. Methods for determining a compound's PSA can be found, e.g., Ertl et al. (2000) J. Med. Chem. 43:3714-3717 and Kelder et al. (1999) Pharm. Res. 16:1514-1519.

With respect to the blood-brain barrier, the water-soluble, non-peptidic oligomer-containing compound of the invention exhibits a blood-brain barrier crossing rate that is reduced as compared to the crossing rate of the small molecule drug not attached to the water-soluble, non-peptidic oligomer. Exemplary reductions in blood-brain barrier crossing rates for the compounds described herein include reductions of: at least about 5%; at least about 10%; at least about 25%; at least about 30%; at least about 40%; at least about 50%; at least about 60%; at least about 70%; at least about 80%; or at least about 90%, when compared to the blood-brain barrier crossing rate of the corresponding compound lacking water-soluble, non-peptic oligomers. A preferred reduction in the blood-brain barrier crossing rate for a conjugate of the invention is at least about 20%.

Assays for determining whether a given compound (regardless of whether the compound includes a water-soluble, non-peptidic oligomer or not) can act as a 3-alkoxypropionamide are known and/or may be prepared by one of ordinary skill in the art and are further described infra.

Briefly, one approach for testing whether a given 3-alkoxypropionamide has a decrease in cerebral excitability (as demonstrated by the audiogenic seizure test in mice) is described in Swinyard et al. (1963) Procedures International Conference on Psychophysiology, Neuropharmacology, and Biochemistry of Audiogenic Seizures Paris, France: International Colloquium No. 112:405-427. Using this approach, preferred 3-alkoxypropionamides (and compounds of the invention) will be shown to be active in the tonic phase of the audiogenic seizure at the intraperitoneally administered dose of about 200 mg/kg of body weight.

Each of these (and other) 3-alkoxypropionamide can be covalently attached (either directly or through one or more atoms) to a water-soluble, non-peptidic oligomer.

Exemplary molecular weights of a small molecule 3-alkoxypropionamide (prior to, for example, conjugation to a water-soluble, non-peptidic oligomer) include molecular weights of: less than about 950; less than about 900; less than about 850; less than about 800; less than about 750; less than about 700; less than about 650; less than about 600; less than about 550; less than about 500; less than about 450; less than about 400; less than about 350; and less than about 300 Daltons.

The small molecule drug used in the invention, if chiral, may be obtained from a racemic mixture, or an optically active form, for example, a single optically active enantiomer, or any combination or ratio of enantiomers (e.g., scalemic and racemic mixtures). In addition, the small molecule drug may possess one or more geometric isomers. With respect to geometric isomers, a composition can comprise a single geometric isomer or a mixture of two or more geometric isomers. A small molecule drug for use in the present invention can be in its customary active form, or may possess some degree of modification. For example, a small molecule drug may have a targeting agent, tag, or transporter attached thereto, prior to or after covalent attachment of an oligomer. Alternatively, the small molecule drug may possess a lipophilic moiety attached thereto, such as a phospholipid (e.g., distearoylphosphatidylethanolamine or “DSPE,” dipalmitoylphosphatidylethanolamine or “DPPE,” and so forth) or a small fatty acid. In some instances, however, it is preferred that the small molecule drug moiety does not include attachment to a lipophilic moiety.

The 3-alkoxypropionamide for coupling to a water-soluble, non-peptidic oligomer possesses a free hydroxyl, carboxyl, thio, amino group, or the like (i.e., “handle”) suitable for covalent attachment to the oligomer. In addition, the 3-alkoxypropionamide may be modified by introduction of a reactive group, preferably by conversion of one of its existing functional groups to a functional group suitable for formation of a stable covalent linkage between the oligomer and the drug.

Each oligomer is composed of up to three different monomer types selected from the group consisting of: alkylene oxide, such as ethylene oxide or propylene oxide; olefinic alcohol, such as vinyl alcohol, 1-propenol or 2-propenol; vinyl pyrrolidone; hydroxyalkyl methacrylamide or hydroxyalkyl methacrylate, where alkyl is preferably methyl; α-hydroxy acid, such as lactic acid or glycolic acid; phosphazene, oxazoline, amino acids, carbohydrates such as monosaccharides, alditol such as mannitol; and N-acryloylmorpholine. Preferred monomer types include alkylene oxide, olefinic alcohol, hydroxyalkyl methacrylamide or methacrylate, N-acryloylmorpholine, and α-hydroxy acid. Preferably, each oligomer is, independently, a co-oligomer of two monomer types selected from this group, or, more preferably, is a homo-oligomer of one monomer type selected from this group.

The two monomer types in a co-oligomer may be of the same monomer type, for example, two alkylene oxides, such as ethylene oxide and propylene oxide. Preferably, the oligomer is a homo-oligomer of ethylene oxide. Usually, although not necessarily, the terminus (or termini) of the oligomer that is not covalently attached to a small molecule is capped to render it unreactive. Alternatively, the terminus may include a reactive group. When the terminus is a reactive group, the reactive group is either selected such that it is unreactive under the conditions of formation of the final oligomer or during covalent attachment of the oligomer to a small molecule drug, or it is protected as necessary. One common end-functional group is hydroxyl or —OH, particularly for oligoethylene oxides.

The water-soluble, non-peptidic oligomer (e.g., “POLY¹” in various structures provided herein) can have any of a number of different geometries. For example, the water-soluble, non-peptidic oligomer can be linear, branched, or forked. Most typically, the water-soluble, non-peptidic oligomer is linear or is branched, for example, having one branch point. Although much of the discussion herein is focused upon poly(ethylene oxide) as an illustrative oligomer, the discussion and structures presented herein can be readily extended to encompass any water-soluble, non-peptidic oligomers described above.

The molecular weight of the water-soluble, non-peptidic oligomer, excluding the linker portion, is generally relatively low. Exemplary values of the molecular weight of the water-soluble polymer include: below about 1500; below about 1450; below about 1400; below about 1350; below about 1300; below about 1250; below about 1200; below about 1150; below about 1100; below about 1050; below about 1000; below about 950; below about 900; below about 850; below about 800; below about 750; below about 700; below about 650; below about 600; below about 550; below about 500; below about 450; below about 400; below about 350; below about 300; below about 250; below about 200; and below about 100 Daltons.

Exemplary ranges of molecular weights of the water-soluble, non-peptidic oligomer (excluding the linker) include: from about 100 to about 1400 Daltons; from about 100 to about 1200 Daltons; from about 100 to about 800 Daltons; from about 100 to about 500 Daltons; from about 100 to about 400 Daltons; from about 200 to about 500 Daltons; from about 200 to about 400 Daltons; from about 75 to 1000 Daltons; and from about 75 to about 750 Daltons.

Preferably, the number of monomers in the water-soluble, non-peptidic oligomer falls within one or more of the following ranges: between about 1 and about 30 (inclusive); between about 1 and about 25; between about 1 and about 20; between about 1 and about 15; between about 1 and about 12; between about 1 and about 10. In certain instances, the number of monomers in series in the oligomer (and the corresponding conjugate) is one of 1, 2, 3, 4, 5, 6, 7, or 8. In additional embodiments, the oligomer (and the corresponding conjugate) contains 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 monomers. In yet further embodiments, the oligomer (and the corresponding conjugate) possesses 21, 22, 23, 24, 25, 26, 27, 28, 29 or 30 monomers in series. Thus, for example, when the water-soluble, non-peptidic polymer includes CH₃—(OCH₂CH₂)_(n)—, “n” is an integer that can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 or 30, and can fall within one or more of the following ranges: between about 1 and about 25; between about 1 and about 20; between about 1 and about 15; between about 1 and about 12; between about 1 and about 10.

When the water-soluble, non-peptidic oligomer has 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 monomers, these values correspond to a methoxy end-capped oligo(ethylene oxide) having a molecular weights of about 75, 119, 163, 207, 251, 295, 339, 383, 427, and 471 Daltons, respectively. When the oligomer has 11, 12, 13, 14, or 15 monomers, these values correspond to methoxy end-capped oligo(ethylene oxide) having molecular weights corresponding to about 515, 559, 603, 647, and 691 Daltons, respectively.

When the water-soluble, non-peptidic oligomer is attached to the 3-alkoxypropionamide (in contrast to the step-wise addition of one or more monomers to effectively “grow” the oligomer onto the 3-alkoxypropionamide), it is preferred that the composition containing an activated form of the water-soluble, non-peptidic oligomer be monodisperse. In those instances, however, where a bimodal composition is employed, the composition will possess a bimodal distribution centering around any two of the above numbers of monomers. For instance, a bimodal oligomer may have any one of the following exemplary combinations of monomer subunits: 1-2, 1-3, 1-4, 1-5, 1-6, 1-7, 1-8, 1-9, 1-10, and so forth; 2-3, 2-4, 2-5, 2-6, 2-7, 2-8, 2-9, 2-10, and so forth; 3-4, 3-5, 3-6, 3-7, 3-8, 3-9, 3-10, and so forth; 4-5, 4-6, 4-7, 4-8, 4-9, 4-10, and so forth; 5-6, 5-7, 5-8, 5-9, 5-10, and so forth; 6-7, 6-8, 6-9, 6-10, and so forth; 7-8, 7-9, 7-10, and so forth; and 8-9, 8-10, and so forth.

In some instances, the composition containing an activated form of the water-soluble, non-peptidic oligomer will be trimodal or even tetramodal, possessing a range of monomers units as previously described. Oligomer compositions possessing a well-defined mixture of oligomers (i.e., being bimodal, trimodal, tetramodal, and so forth) can be prepared by mixing purified monodisperse oligomers to obtain a desired profile of oligomers (a mixture of two oligomers differing only in the number of monomers is bimodal; a mixture of three oligomers differing only in the number of monomers is trimodal; a mixture of four oligomers differing only in the number of monomers is tetramodal), or alternatively, can be obtained from column chromatography of a polydisperse oligomer by recovering the “center cut”, to obtain a mixture of oligomers in a desired and defined molecular weight range.

It is preferred that the water-soluble, non-peptidic oligomer is obtained from a composition that is preferably unimolecular or monodisperse. That is, the oligomers in the composition possess the same discrete molecular weight value rather than a distribution of molecular weights. Some monodisperse oligomers can be purchased from commercial sources such as those available from Sigma-Aldrich, or alternatively, can be prepared directly from commercially available starting materials such as Sigma-Aldrich. Water-soluble, non-peptidic oligomers can be prepared as described in Chen Y., Baker, G. L., J. Org. Chem., 6870-6873 (1999), WO 02/098949, and U.S. Patent Application Publication No. 2005/0136031.

The spacer moiety (the linkage through which the water-soluble, non-peptidic polymer is attached to the 3-alkoxypropionamide) may be a single bond, a single atom, such as an oxygen atom or a sulfur atom, two atoms, or a number of atoms. A spacer moiety is typically but is not necessarily linear in nature. The spacer moiety, “X,” is preferably hydrolytically stable, and is also preferably enzymatically stable. Preferably, the spacer moiety “X” is one having a chain length of less than about 12 atoms, and preferably less than about 10 atoms, and even more preferably less than about 8 atoms and even more preferably less than about 5 atoms, whereby length is meant the number of atoms in a single chain, not counting substituents. For instance, a urea linkage such as this, R_(oligomer)—NH—(C═O)—NH—R′_(drug), is considered to have a chain length of 3 atoms (—NH—C(O)—NH—). In selected embodiments, the linkage does not comprise further spacer groups.

In some instances, the spacer moiety (e.g., “X¹” in various structures provided herein) comprises an ether, amide, urethane, amine, thioether, urea, or a carbon-carbon bond. Functional groups such as those discussed below, and illustrated in the examples, are typically used for forming the linkages. The spacer moiety may less preferably also comprise (or be adjacent to or flanked by) other atoms, as described further below.

More specifically, in selected embodiments, a spacer moiety (e.g., “X¹” in various structures provided herein) may be any of the following: “-” (i.e., a covalent bond, that may be stable or degradable, between the pyrrolidine residue and the water-soluble, non-peptidic oligomer), —O—, —NH—, —S—, —C(O)—, —C(O)O—, —OC(O)—, —CH₂—C(O)O—, —CH₂—OC(O)—, —C(O)O—CH₂—, —OC(O)—CH₂—, C(O)—NH, NH—C(O)—NH, O—C(O)—NH, —C(S)—, —CH₂—, —CH₂—CH₂—, —CH₂—CH₂—CH₂—, —CH₂—CH₂—CH₂—CH₂—, —O—CH₂—, —CH₂—O—, —O—CH₂—CH₂—, —CH₂—O—CH₂—, —CH₂—CH₂—O—, —O—CH₂—CH₂—CH₂—, —CH₂—O—CH₂—CH₂—, —CH₂—CH₂—O—CH₂—, —CH₂—CH₂—CH₂—O—, —O—CH₂—CH₂—CH₂—CH₂—, —CH₂—O—CH₂—CH₂—CH₂—, —CH₂—CH₂—O—CH₂—CH₂—, —CH₂—CH₂—CH₂—O—CH₂—, —CH₂—CH₂—CH₂—CH₂—O—, —C(O)—NH—CH₂—, —C(O)—NH—CH₂—CH₂—, —CH₂—C(O)—NH—CH₂—, —CH₂—CH₂—C(O)—NH—, —C(O)—NH—CH₂—CH₂—CH₂—, —CH₂—C(O)—NH—CH₂—CH₂—, —CH₂—CH₂—C(O)—NH—CH₂—, —CH₂—CH₂—CH₂—C(O)—NH—, —C(O)—NH—CH₂—CH₂—CH₂—CH₂—, —CH₂—C(O)—NH—CH₂—CH₂—CH₂—, —CH₂—CH₂—C(O)—NH—CH₂—CH₂—, —CH₂—CH₂—CH₂—C(O)—NH—CH₂—, —CH₂—CH₂—CH₂—C(O)—NH—CH₂—CH₂—, —CH₂—CH₂—CH₂—CH₂—C(O)—NH—, —NH—C(O)—CH₂—, —CH₂—NH—C(O)—CH₂—, —CH₂—CH₂—NH—C(O)—CH₂—, —NH—C(O)—CH₂—CH₂—, —CH₂—NH—C(O)—CH₂—CH₂, —CH₂—CH₂—NH—C(O)—CH₂—CH₂, —C(O)—NH—CH₂—, —C(O)—NH—CH₂—CH₂—, —O—C(O)—NH—CH₂—, —O—C(O)—NH—CH₂—CH₂—, —NH—CH₂—, —NH—CH₂—CH₂—, —CH₂—NH—CH₂—, —CH₂—CH₂—NH—CH₂—, —C(O)—CH₂—, —C(O)—CH₂—CH₂—, —CH₂—C(O)—CH₂—, —CH₂—CH₂—C(O)—CH₂—, —CH₂—CH₂—C(O)—CH₂—CH₂—, —CH₂—CH₂—C(O)—, —CH₂—CH₂—CH₂—C(O)—NH—CH₂—CH₂—NH—, —CH₂—CH₂—CH₂—C(O)—NH—CH₂—CH₂—NH—C(O)—, —CH₂—CH₂—CH₂—C(O)—NH—CH₂—CH₂—NH—C(O)—CH₂—, bivalent cycloalkyl group, —N(R⁶)—, R⁶ is H or an organic radical selected from the group consisting of alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, aryl and substituted aryl. Additional spacer moieties include, acylamino, acyl, aryloxy, alkylene bridge containing between 1 and 5 inclusive carbon atoms, alkylamino, dialkylamino having about 2 to 4 inclusive carbon atoms, piperidino, pyrrolidino, N-(lower alkyl)-2-piperidyl, morpholino, 1-piperizinyl, 4-(lower alkyl)-1-piperizinyl, 4-(hydroxyl-lower alkyl)-1-piperizinyl, 4-(methoxy-lower alkyl)-1-piperizinyl, and guanidine. In some instances, a portion or a functional group of the drug compound may be modified or removed altogether to facilitate attachment of the oligomer.

For purposes of the present invention, however, a group of atoms is not considered a linkage when it is immediately adjacent to an oligomer segment, and the group of atoms is the same as a monomer of the oligomer such that the group would represent a mere extension of the oligomer chain.

The spacer moiety between the water-soluble, non-peptidic oligomer and the small molecule is formed by reaction of a functional group on a terminus of the oligomer (or nascent oligomer when it is desired to “grow” the oligomer onto the pyrrolidine) with a corresponding functional group within the pyrrolidine. Illustrative reactions are described briefly below. For example, an amino group on an oligomer may be reacted with a carboxylic acid or an activated carboxylic acid derivative on the small molecule, or vice versa, to produce an amide linkage. Alternatively, reaction of an amine on an oligomer with an activated carbonate (e.g., succinimidyl or benzotriazolyl carbonate) on the drug, or vice versa, forms a carbamate linkage. Reaction of an amine on an oligomer with an isocyanate (R—N═C═O) on a drug, or vice versa, forms a urea linkage (R—NH—(C═O)—NH—R′). Further, reaction of an alcohol (alkoxide) group on an oligomer with an alkyl halide, or halide group within a drug, or vice versa, forms an ether linkage. In yet another coupling approach, a small molecule having an aldehyde function is coupled to an oligomer amino group by reductive amination, resulting in formation of a secondary amine linkage between the oligomer and the small molecule.

A particularly preferred water-soluble, non-peptidic oligomer is an oligomer bearing an aldehyde functional group. In this regard, the oligomer will have the following structure: CH₃O—(CH₂—CH₂—O)_(n)—(CH₂)_(p)—C(O)H, wherein (n) is one of 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 and (p) is one of 1, 2, 3, 4, 5, 6 and 7. Preferred (n) values include 3, 5 and 7 and preferred (p) values 2, 3 and 4.

The termini of the water-soluble, non-peptidic oligomer not bearing a functional group may be capped to render it unreactive. When the oligomer includes a further functional group at a terminus other than that intended for formation of a conjugate, that group is either selected such that it is unreactive under the conditions of formation of the spacer moiety (e.g., “X”) or it is protected during the formation of the spacer moiety (e.g., “X¹”).

As stated above, the water-soluble, non-peptidic oligomer includes at least one functional group prior to conjugation. The functional group comprises an electrophilic or nucleophilic group for covalent attachment to a small molecule, depending upon the reactive group contained within or introduced into the small molecule. Examples of nucleophilic groups that may be present in either the oligomer or the small molecule include hydroxyl, amine, hydrazine (—NHNH₂), hydrazide (—C(O)NHNH₂), and thiol. Preferred nucleophiles include amine, hydrazine, hydrazide, and thiol, particularly amine. Most small molecule drugs for covalent attachment to an oligomer will possess a free hydroxyl, amino, thio, aldehyde, ketone, or carboxyl group.

Examples of electrophilic functional groups that may be present in either the oligomer or the small molecule include carboxylic acid, carboxylic ester, particularly imide esters, orthoester, carbonate, isocyanate, isothiocyanate, aldehyde, ketone, thione, alkenyl, acrylate, methacrylate, acrylamide, sulfone, maleimide, disulfide, iodo, epoxy, sulfonate, thiosulfonate, silane, alkoxysilane, and halosilane. More specific examples of these groups include succinimidyl ester or carbonate, imidazoyl ester or carbonate, benzotriazole ester or carbonate, vinyl sulfone, chloroethylsulfone, vinylpyridine, pyridyl disulfide, iodoacetamide, glyoxal, dione, mesylate, tosylate, and tresylate (2,2,2-trifluoroethanesulfonate).

Also included are sulfur analogs of several of these groups, such as thione, thione hydrate, thioketal, 2-thiazolidine thione, etc., as well as hydrates or protected derivatives of any of the above moieties (e.g., aldehyde hydrate, hemiacetal, acetal, ketone hydrate, hemiketal, ketal, thioketal, thioacetal).

An “activated derivative” of a carboxylic acid refers to a carboxylic acid derivative that reacts readily with nucleophiles, generally much more readily than the underivatized carboxylic acid. Activated carboxylic acids include, for example, acid halides (such as acid chlorides), anhydrides, carbonates, and esters. Such esters include imide esters, of the general form —(CO)O—N[(CO)—]₂; for example, N-hydroxysuccinimidyl (NHS) esters or N-hydroxyphthalimidyl esters. Also preferred are imidazolyl esters and benzotriazole esters. Particularly preferred are activated propionic acid or butanoic acid esters, as described in co-owned U.S. Pat. No. 5,672,662. These include groups of the form —(CH₂)₂₋₃C(═O)O-Q, where Q is preferably selected from N-succinimide, N-sulfosuccinimide, N-phthalimide, N-glutarimide, N-tetrahydrophthalimide, N-norbornene-2,3-dicarboximide, benzotriazole, 7-azabenzotriazole, and imidazole.

Other preferred electrophilic groups include succinimidyl carbonate, maleimide, benzotriazole carbonate, glycidyl ether, imidazoyl carbonate, p-nitrophenyl carbonate, acrylate, tresylate, aldehyde, and orthopyridyl disulfide.

These electrophilic groups are subject to reaction with nucleophiles, e.g., hydroxy, thio, or amino groups, to produce various bond types. Preferred for the present invention are reactions which favor formation of a hydrolytically stable linkage. For example, carboxylic acids and activated derivatives thereof, which include orthoesters, succinimidyl esters, imidazolyl esters, and benzotriazole esters, react with the above types of nucleophiles to form esters, thioesters, and amides, respectively, of which amides are the most hydrolytically stable. Carbonates, including succinimidyl, imidazolyl, and benzotriazole carbonates, react with amino groups to form carbamates. Isocyanates (R—N═C═O) react with hydroxyl or amino groups to form, respectively, carbamate (RNH—C(O)—OR′) or urea (RNH—C(O)—NHR′) linkages. Aldehydes, ketones, glyoxals, diones and their hydrates or alcohol adducts (i.e., aldehyde hydrate, hemiacetal, acetal, ketone hydrate, hemiketal, and ketal) are preferably reacted with amines, followed by reduction of the resulting imine, if desired, to provide an amine linkage (reductive amination).

Several of the electrophilic functional groups include electrophilic double bonds to which nucleophilic groups, such as thiols, can be added, to form, for example, thioether bonds. These groups include maleimides, vinyl sulfones, vinyl pyridine, acrylates, methacrylates, and acrylamides. Other groups comprise leaving groups that can be displaced by a nucleophile; these include chloroethyl sulfone, pyridyl disulfides (which include a cleavable S—S bond), iodoacetamide, mesylate, tosylate, thiosulfonate, and tresylate. Epoxides react by ring opening by a nucleophile, to form, for example, an ether or amine bond. Reactions involving complementary reactive groups such as those noted above on the oligomer and the small molecule are utilized to prepare the conjugates of the invention.

In some instances the 3-alkoxypropionamide may not have a functional group suited for conjugation. In this instance, it is possible to modify (or “functionalize”) the “original” 3-alkoxypropionamide so that it does have a functional group suited for conjugation. For example, if the 3-alkoxypropionamide has an amide group, but an amine group is desired, it is possible to modify the amide group to an amine group by way of a Hofmann rearrangement, Curtius rearrangement (once the amide is converted to an azide) or Lossen rearrangement (once amide is concerted to hydroxamide followed by treatment with tolyene-2-sulfonyl chloride/base).

It is possible to prepare a conjugate of 3-alkoxypropionamide bearing a carboxyl group wherein the carboxyl group-bearing 3-alkoxypropionamide is coupled to an amino-terminated oligomeric ethylene glycol, to provide a conjugate having an amide group covalently linking the 3-alkoxypropionamide to the oligomer. This can be performed, for example, by combining the carboxyl group-bearing 3-alkoxypropionamide with the amino-terminated oligomeric ethylene glycol in the presence of a coupling reagent, (such as dicyclohexylcarbodiimide or “DCC”) in an anhydrous organic solvent.

Further, it is possible to prepare a conjugate of a 3-alkoxypropionamide bearing a hydroxyl group wherein the hydroxyl group-bearing 3-alkoxypropionamide is coupled to an oligomeric ethylene glycol halide to result in an ether (—O—) linked conjugate. This can be performed, for example, by using sodium hydride to deprotonate the hydroxyl group followed by reaction with a halide-terminated oligomeric ethylene glycol.

Further, it is possible to prepare a conjugate of a 3-alkoxypropionamide bearing a hydroxyl group wherein the hydroxyl group-bearing 3-alkoxypropionamide is coupled to an oligomeric ethylene glycol bearing an haloformate group [e.g., CH₃(OCH₂CH₂)_(n)OC(O)-halo, where halo is chloro, bromo, iodo] to result in a carbonate [—O—C(O)—O—] linked small molecule conjugate. This can be performed, for example, by combining a 3-alkoxypropionamide and an oligomeric ethylene glycol bearing a haloformate group in the presence of a nucleophilic catalyst (such as 4-dimethylaminopyridine or “DMAP”) to thereby result in the corresponding carbonate-linked conjugate.

In another example, it is possible to prepare a conjugate of a 3-alkoxypropionamide bearing a ketone group by first reducing the ketone group to form the corresponding hydroxyl group. Thereafter, the 3-alkoxypropionamide now bearing a hydroxyl group can be coupled as described herein.

In still another instance, it is possible to prepare a conjugate of a 3-alkoxypropionamide bearing an amine group. In one approach, the amine group-bearing 3-alkoxypropionamide and an aldehyde-bearing oligomer are dissolved in a suitable buffer after which a suitable reducing agent (e.g., NaCNBH₃) is added. Following reduction, the result is an amine linkage formed between the amine group of the amine group-containing 3-alkoxypropionamide and the carbonyl carbon of the aldehyde-bearing oligomer.

In another approach for preparing a conjugate of a 3-alkoxypropionamide bearing an amine group, a carboxylic acid-bearing oligomer and the amine group-bearing 3-alkoxypropionamide are combined, in the presence of a coupling reagent (e.g., DCC). The result is an amide linkage formed between the amine group of the amine group-containing 3-alkoxypropionamide and the carbonyl of the carboxylic acid-bearing oligomer.

While it is believed that the full scope of the compounds disclosed herein behave as described, an optimally sized oligomer can be identified as follows.

First, an oligomer obtained from a monodisperse or bimodal water soluble oligomer is conjugated to the 3-alkoxypropionamide. Preferably, the drug is orally bioavailable, and on its own, exhibits a non-negligible blood-brain barrier crossing rate. Next, the ability of the conjugate to cross the blood-brain barrier is determined using an appropriate model and compared to that of the unmodified parent drug. If the results are favorable, that is to say, if, for example, the rate of crossing is significantly reduced, then the bioactivity of conjugate is further evaluated. Preferably, the compounds according to the invention maintain a significant degree of bioactivity relative to the parent drug, i.e., greater than about 30% of the bioactivity of the parent drug, or even more preferably, greater than about 50% of the bioactivity of the parent drug.

The above steps are repeated one or more times using oligomers of the same monomer type but having a different number of subunits and the results compared.

For each conjugate whose ability to cross the blood-brain barrier is reduced in comparison to the non-conjugated small molecule drug, its oral bioavailability is then assessed. Based upon these results, that is to say, based upon the comparison of conjugates of oligomers of varying size to a given small molecule at a given position or location within the small molecule, it is possible to determine the size of the oligomer most effective in providing a conjugate having an optimal balance between reduction in biological membrane crossing, oral bioavailability, and bioactivity. The small size of the oligomers makes such screenings feasible and allows one to effectively tailor the properties of the resulting conjugate. By making small, incremental changes in oligomer size and utilizing an experimental design approach, one can effectively identify a conjugate having a favorable balance of reduction in biological membrane crossing rate, bioactivity, and oral bioavailability. In some instances, attachment of an oligomer as described herein is effective to actually increase oral bioavailability of the drug.

For example, one of ordinary skill in the art, using routine experimentation, can determine a best suited molecular size and linkage for improving oral bioavailability by first preparing a series of oligomers with different weights and functional groups and then obtaining the necessary clearance profiles by administering the conjugates to a patient and taking periodic blood and/or urine sampling. Once a series of clearance profiles have been obtained for each tested conjugate, a suitable conjugate can be identified.

Animal models (rodents and dogs) can also be used to study oral drug transport. In addition, non-in vivo methods include rodent everted gut excised tissue and Caco-2 cell monolayer tissue-culture models. These models are useful in predicting oral drug bioavailability.

To determine whether the 3-alkoxypropionamide or a compound of the invention (e.g., a conjugate of a 3-alkoxypropionamide and a water-soluble, non-peptidic oligomer) has activity as a 3-alkoxypropionamide therapeutic, it is possible to test such a compound. The compound of interest may be tested using in vitro binding studies to receptors using various cell lines expressing these receptors that have become routine in pharmaceutical industry and described herein.

The compounds of the invention may be administered per se or in the form of a pharmaceutically acceptable salt, and any reference to the compounds of the invention herein is intended to include pharmaceutically acceptable salts. If used, a salt of a compound as described herein should be both pharmacologically and pharmaceutically acceptable, but non-pharmaceutically acceptable salts may conveniently be used to prepare the free active compound or pharmaceutically acceptable salts thereof and are not excluded from the scope of this invention. Such pharmacologically and pharmaceutically acceptable salts can be prepared by reaction of the compound with an organic or inorganic acid, using standard methods detailed in the literature. Examples of useful salts include, but are not limited to, those prepared from the following acids: hydrochloric, hydrobromic, sulfuric, nitric, phosphoric, maleic, acetic, salicyclic, p-toluenesulfonic, tartaric, citric, methanesulfonic, formic, malonic, succinic, naphthalene-2-sulphonic and benzenesulphonic, and the like. Also, pharmaceutically acceptable salts can be prepared as alkaline metal or alkaline earth salts, such as sodium, potassium, or calcium salts of a carboxylic acid group.

The present invention also includes pharmaceutical preparations comprising a compound as provided herein in combination with a pharmaceutical excipient. Generally, the compound itself will be in a solid form (e.g., a precipitate), which can be combined with a suitable pharmaceutical excipient that can be in either solid or liquid form.

Exemplary excipients include, without limitation, those selected from the group consisting of carbohydrates, inorganic salts, antimicrobial agents, antioxidants, surfactants, buffers, acids, bases, and combinations thereof.

A carbohydrate such as a sugar, a derivatized sugar such as an alditol, aldonic acid, an esterified sugar, and/or a sugar polymer may be present as an excipient. Specific carbohydrate excipients include, for example: monosaccharides, such as fructose, maltose, galactose, glucose, D-mannose, sorbose, and the like; disaccharides, such as lactose, sucrose, trehalose, cellobiose, and the like; polysaccharides, such as raffinose, melezitose, maltodextrins, dextrans, starches, and the like; and alditols, such as mannitol, maltitol, lactitol, xylitol, sorbitol, myoinositol, and the like.

The excipient can also include an inorganic salt or buffer such as citric acid, sodium chloride, potassium chloride, sodium sulfate, potassium nitrate, sodium phosphate monobasic, sodium phosphate dibasic, and combinations thereof.

The preparation may also include an antimicrobial agent for preventing or deterring microbial growth. Nonlimiting examples of antimicrobial agents suitable for the present invention include benzalkonium chloride, benzethonium chloride, benzyl alcohol, cetylpyridinium chloride, chlorobutanol, phenol, phenylethyl alcohol, phenylmercuric nitrate, thimersol, and combinations thereof.

An antioxidant can be present in the preparation as well. Antioxidants are used to prevent oxidation, thereby preventing the deterioration of the conjugate or other components of the preparation. Suitable antioxidants for use in the present invention include, for example, ascorbyl palmitate, butylated hydroxyanisole, butylated hydroxytoluene, hypophosphorous acid, monothioglycerol, propyl gallate, sodium bisulfite, sodium formaldehyde sulfoxylate, sodium metabisulfite, and combinations thereof.

A surfactant may be present as an excipient. Exemplary surfactants include: polysorbates, such as “Tween 20” and “Tween 80,” and pluronics such as F68 and F88 (both of which are available from BASF, Mount Olive, N.J.); sorbitan esters; lipids, such as phospholipids such as lecithin and other phosphatidylcholines, phosphatidylethanolamines, fatty acids and fatty esters; steroids, such as cholesterol; and chelating agents, such as EDTA, zinc and other such suitable cations.

Pharmaceutically acceptable acids or bases may be present as an excipient in the preparation. Nonlimiting examples of acids that can be used include those acids selected from the group consisting of hydrochloric acid, acetic acid, phosphoric acid, citric acid, malic acid, lactic acid, formic acid, trichloroacetic acid, nitric acid, perchloric acid, phosphoric acid, sulfuric acid, fumaric acid, and combinations thereof. Examples of suitable bases include, without limitation, bases selected from the group consisting of sodium hydroxide, sodium acetate, ammonium hydroxide, potassium hydroxide, ammonium acetate, potassium acetate, sodium phosphate, potassium phosphate, sodium citrate, sodium formate, sodium sulfate, potassium sulfate, potassium fumerate, and combinations thereof.

The amount of the compound of the invention in the composition will vary depending on a number of factors, but will optimally be a therapeutically effective dose when the composition is stored in a unit dose container. A therapeutically effective dose can be determined experimentally by repeated administration of increasing amounts of the compound in order to determine which amount produces a clinically desired endpoint.

The amount of any individual excipient in the composition will vary depending on the activity of the excipient and particular needs of the composition. The optimal amount of any individual excipient is determined through routine experimentation, i.e., by preparing compositions containing varying amounts of the excipient (ranging from low to high), examining the stability and other parameters, and then determining the range at which optimal performance is attained with no significant adverse effects.

Generally, however, excipients will be present in the composition in an amount of about 1% to about 99% by weight, preferably from about 5%-98% by weight, more preferably from about 15-95% by weight of the excipient, with concentrations less than 30% by weight most preferred.

These foregoing pharmaceutical excipients along with other excipients and general teachings regarding pharmaceutical compositions are described in “Remington: The Science & Practice of Pharmacy”, 19^(th) ed., Williams & Williams, (1995), the “Physician's Desk Reference”, 52^(nd) ed., Medical Economics, Montvale, N.J. (1998), and Kibbe, A. H., Handbook of Pharmaceutical Excipients, 3rd Edition, American Pharmaceutical Association, Washington, D.C., 2000.

The pharmaceutical compositions can take any number of forms and the invention is not limited in this regard. Exemplary preparations are most preferably in a form suitable for oral administration such as a tablet, caplet, capsule, gel cap, troche, dispersion, suspension, solution, elixir, syrup, lozenge, transdermal patch, spray, suppository, and powder.

Oral dosage forms are preferred for those conjugates that are orally active, and include tablets, caplets, capsules, gel caps, suspensions, solutions, elixirs, and syrups, and can also comprise a plurality of granules, beads, powders or pellets that are optionally encapsulated. Such dosage forms are prepared using conventional methods known to those in the field of pharmaceutical formulation and described in the pertinent texts.

Tablets and caplets, for example, can be manufactured using standard tablet processing procedures and equipment. Direct compression and granulation techniques are preferred when preparing tablets or caplets containing the conjugates described herein. In addition to the conjugate, the tablets and caplets will generally contain inactive, pharmaceutically acceptable carrier materials such as binders, lubricants, disintegrants, fillers, stabilizers, surfactants, coloring agents, flow agents, and the like. Binders are used to impart cohesive qualities to a tablet, and thus ensure that the tablet remains intact. Suitable binder materials include, but are not limited to, starch (including corn starch and pregelatinized starch), gelatin, sugars (including sucrose, glucose, dextrose and lactose), polyethylene glycol, waxes, and natural and synthetic gums, e.g., acacia sodium alginate, polyvinylpyrrolidone, cellulosic polymers (including hydroxypropyl cellulose, hydroxypropyl methylcellulose, methyl cellulose, microcrystalline cellulose, ethyl cellulose, hydroxyethylcellulose, and the like), and Veegum. Lubricants are used to facilitate tablet manufacture, promoting powder flow and preventing particle capping (i.e., particle breakage) when pressure is relieved. Useful lubricants are magnesium stearate, calcium stearate, and stearic acid. Disintegrants are used to facilitate disintegration of the tablet, and are generally starches, clays, celluloses, algins, gums, or crosslinked polymers. Fillers include, for example, materials such as silicon dioxide, titanium dioxide, alumina, talc, kaolin, powdered cellulose, and microcrystalline cellulose, as well as soluble materials such as mannitol, urea, sucrose, lactose, dextrose, sodium chloride, and sorbitol. Stabilizers, as well known in the art, are used to inhibit or retard drug decomposition reactions that include, by way of example, oxidative reactions.

Capsules are also preferred oral dosage forms, in which case the conjugate-containing composition can be encapsulated in the form of a liquid or gel (e.g., in the case of a gel cap) or solid (including particulates such as granules, beads, powders or pellets). Suitable capsules include hard and soft capsules, and are generally made of gelatin, starch, or a cellulosic material. Two-piece hard gelatin capsules are preferably sealed, such as with gelatin bands or the like.

Included are parenteral formulations in the substantially dry form (as a lyophilizate or precipitate, which can be in the form of a powder or cake), as well as formulations prepared for injection, which are liquid and require the step of reconstituting the dry form of parenteral formulation. Examples of suitable diluents for reconstituting solid compositions prior to injection include bacteriostatic water for injection, dextrose 5% in water, phosphate-buffered saline, Ringer's solution, saline, sterile water, deionized water, and combinations thereof.

In some cases, compositions intended for parenteral administration can take the form of nonaqueous solutions, suspensions, or emulsions, normally being sterile. Examples of nonaqueous solvents or vehicles are propylene glycol, polyethylene glycol, vegetable oils, such as olive oil and corn oil, gelatin, and injectable organic esters such as ethyl oleate.

The parenteral formulations described herein can also contain adjuvants such as preserving, wetting, emulsifying, and dispersing agents. The formulations are rendered sterile by incorporation of a sterilizing agent, filtration through a bacteria-retaining filter, irradiation, or heat.

The compounds of the invention can also be administered through the skin using conventional transdermal patch or other transdermal delivery system, wherein the conjugate is contained within a laminated structure that serves as a drug delivery device to be affixed to the skin. In such a structure, the compound is contained in a layer, or “reservoir,” underlying an upper backing layer. The laminated structure can contain a single reservoir, or it can contain multiple reservoirs.

The compounds of the invention can also be formulated into a suppository for rectal administration. With respect to suppositories, the compound is mixed with a suppository base material which is (e.g., an excipient that remains solid at room temperature but softens, melts or dissolves at body temperature) such as cocoa butter (theobroma oil), polyethylene glycols, glycerinated gelatin, fatty acids, and combinations thereof. Suppositories can be prepared by, for example, performing the following steps (not necessarily in the order presented): melting the suppository base material to form a melt; incorporating the compound (either before or after melting of the suppository base material); pouring the melt into a mold; cooling the melt (e.g., placing the melt-containing mold in a room temperature environment) to thereby form suppositories; and removing the suppositories from the mold.

In some embodiments of the invention, the compositions comprising the compounds of the invention may further be incorporated into a suitable delivery vehicle. Such delivery vehicles may provide controlled and/or continuous release of the compounds and may also serve as a targeting moiety. Non-limiting examples of delivery vehicles include, adjuvants, synthetic adjuvants, microcapsules, microparticles, liposomes, and yeast cell wall particles. Yeast cells walls may be variously processed to selectively remove protein component, glucan, or mannan layers, and are referred to as whole glucan particles (WGP), yeast beta-glucan mannan particles (YGMP), yeast glucan particles (YGP), Rhodotorula yeast cell particles (YCP). Yeast cells such as S. cerevisiae and Rhodotorula species are preferred; however, any yeast cell may be used. These yeast cells exhibit different properties in terms of hydrodynamic volume and also differ in the target organ where they may release their contents. The methods of manufacture and characterization of these particles are described in U.S. Pat. Nos. 5,741,495, 4,810,646, 4,992,540, 5,028,703 and 5,607,677, and U.S. Patent Application Publication Nos. 2005/0281781 and 2008/0044438.

The invention also provides a method for administering a compound of the invention as provided herein to a patient suffering from a condition that is responsive to treatment with the compound. The method comprises administering, generally orally, a therapeutically effective amount of the compound (preferably provided as part of a pharmaceutical preparation). Other modes of administration are also contemplated, such as pulmonary, nasal, buccal, rectal, sublingual, transdermal, and parenteral. As used herein, the term “parenteral” includes subcutaneous, intravenous, intra-arterial, intraperitoneal, intracardiac, intrathecal, and intramuscular injection, as well as infusion injections.

In instances where parenteral administration is utilized, it may be necessary to employ somewhat bigger oligomers than those described previously, with molecular weights ranging from about 500 to 30K Daltons (e.g., having molecular weights of about 500, 1000, 2000, 2500, 3000, 5000, 7500, 10000, 15000, 20000, 25000, 30000 or even more).

The method of administering may be used to treat any condition that can be remedied or prevented by administration of a particular compound of the invention. Those of ordinary skill in the art appreciate which conditions a specific compound can effectively treat. Exemplary conditions include epileptic conditions and pain (e.g., neuropathic pain). The actual dose to be administered will vary depend upon the age, weight, and general condition of the subject as well as the severity of the condition being treated, the judgment of the health care professional, and conjugate being administered. Therapeutically effective amounts are known to those skilled in the art and/or are described in the pertinent reference texts and literature. Generally, a therapeutically effective amount will range from about 0.001 mg to 1000 mg, preferably in doses from 0.01 mg/day to 750 mg/day, and more preferably in doses from 0.10 mg/day to 500 mg/day.

The unit dosage of any given compound of the invention (again, preferably provided as part of a pharmaceutical preparation) can be administered in a variety of dosing schedules depending on the judgment of the clinician, needs of the patient, and so forth. The specific dosing schedule will be known by those of ordinary skill in the art or can be determined experimentally using routine methods. Exemplary dosing schedules include, without limitation, administration five times a day, four times a day, three times a day, twice daily, once daily, three times weekly, twice weekly, once weekly, twice monthly, once monthly, and any combination thereof. Once the clinical endpoint has been achieved, dosing of the composition is halted.

All articles, books, patents, patent publications and other publications referenced herein are incorporated by reference in their entireties. In the event of an inconsistency between the teachings of this specification and the art incorporated by reference, the meaning of the teachings and definitions in this specification shall prevail (particularly with respect to terms used in the claims appended herein). For example, where the present application and a publication incorporated by reference defines the same term differently, the definition of the term shall be preserved within the teachings of the document from which the definition is located.

EXPERIMENTAL

It is to be understood that while the invention has been described in conjunction with certain preferred and specific embodiments, the foregoing description as well as the examples that follow are intended to illustrate and not limit the scope of the invention. Other aspects, advantages and modifications within the scope of the invention will be apparent to those skilled in the art to which the invention pertains.

All non-PEG chemical reagents referred to in the appended examples are commercially available unless otherwise indicated. The preparation of PEG-mers is described in, for example, U.S. Patent Application Publication No. 2005/0136031.

¹H NMR (nuclear magnetic resonance) data was generated by an NMR spectrometer.

Example 1 Synthesis of N-Optionally Substituted Aryl-2-Oligomer-3-Alkoxypropionamides

An exemplary approach for preparing the N-optionally substituted aryl-2-oligomer-3-alkoxypropionamide, (2R) N-benzyl-2-carboxy mPEG_(n) amino-3-methoxy propionamide is provided in the schematic below.

Synthesis of (R)-2-N-Boc-amino-3-methoxypropanoic acid

A suspension of N-Boc-D-serine (17.6 g, 86 mmol) and tetrabutylammonium bromide (1.04 g, 3.23 mmol) in toluene (90 mL) was cooled with an ice-bath with stirring. To the reaction mixture was added 20% sodium hydroxide (14 mL, 86 mmol) and the resulting mixture was stirred for thirty minutes. Dimethyl sulphate (43.3 g, 343 mmol) and 50% sodium hydroxide (20.3 mL, 388 mmol) were added and the reaction mixture was stirred at <10° C. for 3 hours. Water (60 ml) was then added to the mixture and the resulting two phases were separated. The aqueous phase was washed with dichloromethane (100 mL×2). The aqueous phase was then acidified to a pH of <3.5 with 50% citric acid and extracted with methylene chloride (100 mL×3). The organic phases were combined, dried over sodium sulfate, filtered, and solvent removed under reduced pressure to afford a colorless oil (15.6 g, yield: 83%, purity >95%). ¹H NMR (500 MHz, CDCl₃) δ 1.45 (s, 9H), 3.37 (s, 3H), 3.62 (m, 1H), 3.85 (m, 1H), 4.43 (m, 1H), 5.42 (d, 1H). LC-MS (m/z) calculated 219.1, found 242.0 [M+Na]⁺.

Synthesis of (R)—N-Benzyl-2-Boc-amino-3-methoxypropionamide

(R)-2-N-Boc-amino-3-methoxypropanoic acid (15.0 g, 68.4 mmol), phenylmethanamine (7.33 g, 68.4 mmol), and DMAP (4.17 g, 34.2 mmol) were dissolved in DCM (150 mL). The solution was cooled in an ice-bath and EDC (21.21 g, 137 mmol) was added dropwise to the solution. Once addition was complete, the reaction mixture was stirred at warmed to room temperature and stirred for two hours. Then DCM (200 ml) was added to the mixture. The DCM organic phase was washed with H₂O (200 mL×1), 0.5 N HCl (200 mL×2), 5% sodium bicarbonate (200 mL×2) and water (200 mL×2). The organic phase was dried over sodium sulfate, filtered, and solvent removed under reduced pressure. The desired product was obtained as a colorless semi-solid with a purity >95% (9.8 g, 46.4%). ¹H NMR (500 MHz, CDCl₃) δ 1.46 (s, 9H), 3.38 (s, 3H), 3.51 (m, 1H), 3.86 (d, 1H), 4.30 (br., 1H), 4.50 (s, 2H), 5.42 (br., 1H), 6.74 (br., 1H), 7.28 (m, 3H), 7.35 (m, 2H). LC-MS (m/z) calculated. 308.2, found 309.1 [M+H]⁺, 331.1 [M+Na]⁺.

Synthesis of (R)-2-amino-N-benzyl-3-methoxypropanamide

(R)—N— benzyl-2-Boc-amino-3-methoxypropanamide (9.8 g, 31.8 mmol) was dissolved in 15 mL of DCM and then 15 mL of TFA was added to the solution. The mixture was stirred at room temperature for two hours. The solvent and TFA was removed by evaporation and a white solid was obtained (12.4, 100%). Upon analysis, it was determined that on average each molecule contained 1.6 TFA. ¹H NMR (500 MHz, DMSO) δ 3.30 (s, 3H), 3.69 (m, 2H), 4.05 (m, 1H), 4.35 (m, 2H), 7.25 (m, 3H), 7.35 (m, 2H), 8.23 (br., 2H), 8.95 (m, 1H). LC-MS (m/z) calcd. 208.1, found 209.1 [M+H]⁺.

Synthesis of Lacosamide

A solution of acetic anhydride (262 mg, 2.56 mmol) and (R)-2-amino-N-benzyl-3-methoxypropanamide 1.6 TFA (1000 mg, 2.56 mmol) in 10 mL of DCM and triethylamine (3.6 mL, 25.6 mmol) was added. The resulting solution was stirred at room temperature for three hours. DCM (200 mL) was added to the reaction mixture. The resulting solution was washed with H₂O (200 mL), 0.2 N HCl (100 mL), 5% NaHCO₃ (100 mL), and then H₂O (100 mL) and dried over Na₂SO₄. A white solid was obtained after the solvent was removed under reduced pressure. The crude product was purified by crystallization from ethyl acetate/hexane (1:1). The desired product was obtained with a purity of 99% (220 mg, yield: 33.0%). ¹H NMR (500 MHz, CDCl₃) δ 2.05 (s, 3H). 3.39 (s, 3H), 3.45 (t, 1H), 3.84 (m, 1H), 4.48 (s, 2H), 4.56 (m, 1H), 6.44 (br., 1H). 6.74 (br., 1H), 7.28 (m, 3H), 7.36 (m, 2H). LC-MS (m/z) calculated 250.1, found 251.1 [M+H]⁺, 273.1 [M+Na]⁺.

General procedure for the syntheses of (2R) N-benzyl-2-carboxy mPEG_(n) amino-3-methoxy propionamide (n=1, 2, 3, 4, 5, 6, 7, 8, 9).

To a solution of mPEG_(n)-OH (3.0 mmol, n=1, 2, 3, 4, 5, 6, 7, 8, or 9) and N,N-disuccinimidyl carbonate (1150 mg, 4.5 mmol) in 10 mL of CH₃CN was added triethylamine (1.25 mL, 9.0 mmol). The resulting solution was stirred at room temperature for three hours (complete conversion, monitored by HPLC). After the reaction was completed, 100 mL of DCM was added to the reaction mixture. The solution was washed with 5% of NaHCO₃ (50 mL×2) and then with water. The DCM organic phase was then dried, filtered, and the solvent removed under reduced pressure. The product, (mPEG_(n)-succinimidyl carbonate), was obtained as a colorless oil (yields, 80-90%) and was used in the following reactions without further purification.

To a solution of mPEG_(n)-succinimidyl carbonate (2.0 mmol, n=1, 2, 3, 4, 5, 6, 7, 8, or 9) and (R)-2-amino-N-benzyl-3-methoxypropanamide 1.6 TFA (780 mg, 2.0 mmol) in 20 mL of DCM was added triethylamine (2.79 mL, 20.0 mmol). The reaction solution was stirred at room temperature for three hours. Dichloromethane (200 mL) was then added to the reaction mixture and the resulting solution was washed with H₂O (200 mL), 0.2 N HCl (100 mL), 5% NaHCO₃ (100 mL), and then H₂O (100 mL). The organic phase was dried over Na₂SO₄, filtered, and the solvent removed under reduced pressure. The desired product was obtained as a colorless oil (or white solid for n=1, 2, 3) which was then purified by Biotage flash chromatography [MeOH/DCM, 3% MeOH (eq.), 3-5% MeOH, 15 CV, 5% MeOH, 5 CV]. The products, (2R) N-benzyl-2-carboxy mPEG_(n) amino-3-methoxy propionamide (n=1, 2, 3, 4, 5, 6, 7, 8, or 9), were obtained with purities of 97-99%) and yields, 40-65%.

(2R) N-benzyl-2-carboxy mPEG₁ amino-3-methoxy propionamide: ¹H NMR (500 MHz, CDCl₃) δ 3.38 (s, 3H), 3.39 (s, 3H), 3.50 (m, 1H), 3.59 (m, 2H), 3.90 (m, 1H), 4.25 (m, 2H), 4.35 (br., 1H). 4.50 (m, 2H), 5.73 (br., 1H), 6.72 (br., 1H), 7.28 (m, 3H), 7.36 (m, 2H). LC-MS (m/z) calculated 310.1; found, 311.1 [M+H]⁺, 333.1 [M+Na]⁺.

(2R) N-benzyl-2-carboxy mPEG₂ amino-3-methoxy propionamide: ¹H NMR (500 MHz, CDCl₃) δ 3.38 (s, 3H), 3.39 (s, 3H), 3.50 (m, 1H), 3.56 (m, 2H), 3.64 (m, 2H), 3.70 (t, 2H), 3.89 (m, 1H), 4.25 (m, 2H), 4.34 (br., 1H). 4.50 (m, 2H), 5.71 (br., 1H), 6.74 (br., 1H), 7.28 (m, 3H), 7.36 (m, 2H). LC-MS (m/z) calculated 354.2; found, 355.2 [M+H]⁺, 378.1 [M+Na]⁺.

(2R) N-benzyl-2-carboxy mPEG₃ amino-3-methoxy propionamide: ¹H NMR (500 MHz, CDCl₃) δ 3.38 (s, 6H), 3.50 (m, 1H), 3.56 (m, 2H), 3.64 (m, 6H), 3.70 (t, 2H), 3.89 (m, 1H), 4.25 (m, 2H), 4.34 (br., 1H). 4.50 (m, 2H), 5.71 (br., 1H), 6.77 (br., 1H), 7.27 (m, 3H), 7.36 (m, 2H). LC-MS (m/z) calculated 398.2; found, 399.2 [M+H]⁺, 421.1 [M+Na]⁺.

(2R) N-benzyl-2-carboxy mPEG₄ amino-3-methoxy propionamide: ¹H NMR (500 MHz, CDCl₃) δ 3.38 (s, 6H), 3.51 (m, 1H), 3.56 (m, 2H), 3.64 (m, 10H), 3.70 (t, 2H), 3.89 (m, 1H), 4.25 (m, 2H), 4.34 (br., 1H). 4.50 (m, 2H), 5.71 (br., 1H), 6.78 (br., 1H), 7.27 (m, 3H), 7.34 (m, 2H). LC-MS (m/z) calculated 442.2; found, 443.2 [M+H]⁺, 465.2 [M+Na]⁺.

(2R) N-benzyl-2-carboxy mPEG₅ amino-3-methoxy propionamide: ¹H NMR (500 MHz, CDCl₃) δ 3.36 (s, 3H), 3.38 (s, 3H), 3.51 (m, 1H), 3.56 (m, 2H), 3.64 (m, 14H), 3.70 (t, 2H), 3.89 (m, 1H), 4.25 (m, 2H), 4.34 (br., 1H). 4.50 (m, 2H), 5.75 (br., 1H), 6.82 (br., 1H), 7.27 (m, 3H), 7.35 (m, 2H). LC-MS (m/z) calculated 486.2; found, 487.2 [M+H]⁺, 509.2 [M+Na]⁺.

(2R) N-benzyl-2-carboxy mPEG₆ amino-3-methoxy propionamide: ¹H NMR (500 MHz, CDCl₃) δ 3.38 (s, 3H), 3.39 (s, 3H), 3.51 (m, 1H), 3.56 (m, 2H), 3.65 (m, 18H), 3.70 (t, 2H), 3.89 (m, 1H), 4.25 (m, 2H), 4.34 (br., 1H). 4.50 (m, 2H), 5.75 (br., 1H), 6.80 (br., 1H), 7.27 (m, 3H), 7.34 (m, 2H). LC-MS (m/z) calculated 530.3; found, 531.2 [M+H]⁺, 553.2 [M+Na]⁺.

(2R) N-benzyl-2-carboxy mPEG₇ amino-3-methoxy propionamide: ¹H NMR (500 MHz, CDCl₃) δ 3.38 (s, 3H), 3.39 (s, 3H), 3.50 (m, 1H), 3.56 (m, 2H), 3.65 (m, 22H), 3.70 (t, 2H), 3.89 (m, 1H), 4.25 (m, 2H), 4.34 (br., 1H). 4.50 (m, 2H), 5.75 (br., 1H), 6.82 (br., 1H), 7.27 (m, 3H), 7.34 (m, 2H). LC-MS (m/z) calculated 574.3; found, 575.2 [M+H]⁺, 597.2 [M+Na]⁺.

(2R) N-benzyl-2-carboxy mPEG₈ amino-3-methoxy propionamide: ¹H NMR (500 MHz, CDCl₃) δ 3.37 (s, 3H), 3.39 (s, 3H), 3.51 (m, 1H), 3.56 (m, 2H), 3.65 (m, 28H), 3.82 (m, 1H), 4.20 (m, 2H), 4.42 (br., 1H). 4.45 (m, 2H), 5.80 (br., 1H), 6.90 (br., 1H), 7.23 (m, 3H), 7.31 (m, 2H). LC-MS (m/z) calculated 618.3; found, 619.3 [M+H]⁺, 636.2 [M+NH₄]⁺.

(2R) N-benzyl-2-carboxy mPEG₉ amino-3-methoxy propionamide: ¹H NMR (500 MHz, CDCl₃) δ 3.38 (s, 3H), 3.39 (s, 3H), 3.51 (m, 1H), 3.56 (m, 2H), 3.65 (m, 32H), 3.80 (m, 1H), 4.25 (m, 2H), 4.35 (br., 1H). 4.50 (m, 2H), 5.75 (br., 1H), 6.80 (br., 1H), 7.27 (m, 3H), 7.34 (m, 2H). LC-MS (m/z) calculated 662.4; found, 663.3 [M+H]⁺, 680.4 [M+NH₄]⁺.

Example 2 Na⁺ Channel Blocking Examination

Lacosamide, (R)—N-benzyl-2-acetamido-3-methoxy propionamide, is believed to owe at least part of its pharmacologic activity to the inhibition of voltage-gated sodium channels by selectively interacting with the slow-inactivated confirmation of the channel.

Using an automated whole-cell patch-clamp approach, the in vitro effects of oligomer-containing compounds of the invention (synthesis described in Example 1) on cloned hNav1.8 channels expressed in CHO cells relative to control (lacosamide) were evaluated.

The procedures used in this experiment followed those set forth in Sheets et al. (2008) J Pharmacol Exp Ther 326(1):89-99. Briefly, automated patch clamp electrophysiological procedures were carried out in the IonWorks Quattro™ system (Molecular Devices Corporation, Union City Calif.). In preparation for a current recording session, intracellular solution (140 mM KCl, 5 mM MgCl₂, 0.5 mM EGTA, 10 mM HEPES, 0.1 mg/mL amphotericin B) was loaded into the intracellular compartment of the Population Patch Clamp™ (PPC) planar electrode. CHO cells stably expressing the human Nav1.8 sodium channel subtype were suspended in HEPES-buffered physiological saline solution (137 mM NaCl, 4 mM KCl, 1.8 mM CaCl₂, 1 mM MgCl₂, 10 mM HEPES, 10 mM Glucose, pH adjusted to 7.4 with NaOH) and pipetted into the wells of the PPC planar electrode. After establishment of a whole-cell configuration (the perforated patch), membrane currents were recorded using patch clamp amplifier in the IonWorks Quattro™ system. Test article concentrations, loaded in a 384-well compound plate, were applied to naïve cells (one concentration per cell) via steel needles of a 48-channel pipettor. Each application consisted of addition of 6 μL of 2× concentrated test article solution to the total 12 μL final volume of the extracellular well of the PPC planar electrode. The PPC well contents were then mixed (three times) following addition of test article. All experiments were performed at ambient temperature.

Block of hNav1.8 sodium channel was measured using a stimulus voltage pattern shown in FIG. 1, and voltage potentials are indicated in Table 1. The pulse pattern was repeated twice (once before addition of test article and the other five minutes after test article addition). Peak current amplitudes were measured at three test pulses: TP1 (tonic block), TP11 (frequency-dependent block at 10 Hz), and TP12 (inactivated state block).

TABLE 1 Voltage-protocol parameters for hNav1.8 channels Test Pulse Test Holding Pre-Pulse 1-10, 12-14 Pulse 11 Interpulse Test Pulse 1-14 Potential Potential Duration Duration Duration Potential Channel (mV) (mV) (ms) (ms) (ms) (mV) Nav1.8 −80 −120 20 500 80 20

Data acquisition and analyses were performed using the IonWorks Quattro™ system operation software (version 2.0.2; Molecular Devices Corporation, Union City, Calif.). Inhibition potencies were estimated from concentration-response curves fitted using the Hill function: % Block=% VC+{(100−% VC)−(100−% VC)/[1+([Test]/IC₅₀)^(N)]}, where [Test] is the concentration of test article, IC₅₀ is the concentration of the test article producing half-maximal inhibition, N is the Hill coefficient, % VC is the percentage of the current run-down (the mean current inhibition at the vehicle control) and % Block is the percentage of ion channel current inhibited at each concentration of the test article.

As shown in Table 2, the (2R) N-benzyl-2-carboxy mPEG₁ amino-3-methoxy propionamide, (2R) N-benzyl-2-carboxy mPEG₂ amino-3-methoxy propionamide, and (2R) N-benzyl-2-carboxy mPEG₃ amino-3-methoxy propionamide all blocked hNav1.8 channels in the inactivated state with a potency comparable to control (i.e., lacosamide).

TABLE 2 Results of Na⁺ Channel Blocking Examination Type of block IC₅₀ (μM) Inactivated Test compound Tonic 10 Hz state (R)-N-benzyl-2-acetamido-3-methoxy propionamide (lacosamide) >300 >300 278 (2R) N-benzyl-2-carboxy mPEG₁ amino-3-methoxy propionamide >300 >300 267 (2R) N-benzyl-2-carboxy mPEG₂ amino-3-methoxy propionamide >300 >300 166 (2R) N-benzyl-2-carboxy mPEG₃ amino-3-methoxy propionamide >300 >300 239 (2R) N-benzyl-2-carboxy mPEG₄ amino-3-methoxy propionamide >300 >300 >300 (2R) N-benzyl-2-carboxy mPEG₅ amino-3-methoxy propionamide >300 >300 >300 (2R) N-benzyl-2-carboxy mPEG₆ amino-3-methoxy propionamide >300 >300 >300 (2R) N-benzyl-2-carboxy mPEG₇ amino-3-methoxy propionamide >300 >300 >300 (2R) N-benzyl-2-carboxy mPEG₈ amino-3-methoxy propionamide >300 >300 >300 (2R) N-benzyl-2-carboxy mPEG₉ amino-3-methoxy propionamide >300 >300 >300

Example 3 Pain Model—Formalin-Induced Paw Licking in the Mouse

Lacosamide has been proposed for reduction of pain and a pain model based on formalin-induced paw licking was used to evaluate the ability of oligomer-containing compounds to reduce pain.

In the formalin-induced paw licking model, a test compound is administered via oral gavage (“PO”) followed in thirty minutes by the subcutaneous injection of formalin to a hind paw of a mouse. Subcutaneous injection of formalin first causes a pain-inducing mechanical injury (involving bradykinin and substance P) in the first five minutes (“Phase 1”) followed by a pain-inducing inflammatory response (involving bradykinin, histamine, serotonin and prostaglandins) occurring between 15-30 minutes (“Phase 2”) following the formalin injection. Both pain-inducing stimuli causes a characteristic “paw licking” response. The amount of time spent licking the formalin-injected paw is measured during Phase 1 and Phase 2. If the test article has relatively good pain reducing properties, a reduction in the time spent licking the formalin-injected paw is observed compared to the saline control group. In contrast, if the test article has relatively poor pain reducing properties, the duration of the “paw licking” response will be comparable to the saline control group. By measuring a series of test articles, it is possible to understand each test article's pain reducing activity relative to each other. Table 3 lists the test articles administered to the mouse (each test article diluted in 0.5% CMC (carboxymethylcellulose) and all test articles except lacosamide and (2R) N-benzyl-2-carboxy mPEG₁ amino-3-methoxy propionamide were soluble in this vehicle. For the test articles that were not readily soluble, test articles were sonicated and vortexed until a uniform suspension was achieved.

TABLE 3 Test Articles Administered in Formalin-Induced Paw Licking Model Test Article Dose Route Saline — PO (R)-N-benzyl-2-acetamido-3-methoxy propionamide (lacosamide) 200 PO (2R) N-benzyl-2-carboxy mPEG₁ amino-3-methoxy propionamide 200 PO (2R) N-benzyl-2-carboxy mPEG₂ amino-3-methoxy propionamide 200 PO (2R) N-benzyl-2-carboxy mPEG₃ amino-3-methoxy propionamide 200 PO (2R) N-benzyl-2-carboxy mPEG₄ amino-3-methoxy propionamide 200 PO (2R) N-benzyl-2-carboxy mPEG₅ amino-3-methoxy propionamide 200 PO (2R) N-benzyl-2-carboxy mPEG₆ amino-3-methoxy propionamide 200 PO (2R) N-benzyl-2-carboxy mPEG₇ amino-3-methoxy propionamide 200 PO (2R) N-benzyl-2-carboxy mPEG₈ amino-3-methoxy propionamide 200 PO (2R) N-benzyl-2-carboxy mPEG₉ amino-3-methoxy propionamide 200 PO

During the experiment, side effects such as sedation and splayed posture were observed in animals orally dosed with 200 mg/kg lacosamide (Phase 1: 5/7 mice sedated and 5/7 mice with splayed posture, and Phase 2: 6/7 mice sedated and 7/7 splayed posture) and not with any of the oligomer-containing compounds. Furthermore, each of (2R) N-benzyl-2-carboxy mPEG₂ amino-3-methoxy propionamide, (2R) N-benzyl-2-carboxy mPEG₃ amino-3-methoxy propionamide, (2R) N-benzyl-2-carboxy mPEG₄ amino-3-methoxy propionamide, and (2R) N-benzyl-2-carboxy mPEG₅ amino-3-methoxy propionamide showed a reduction in formalin-induced paw licking compared to saline in Phase 2. Lacosamide showed the greatest reduction in formalin-induced paw licking time in both Phase 1 and Phase 2. However, this may be attributed to the side effects observed in both phases. Overall, a reduction in pain response was seen with some of the PEGylated conjugates without the side effects that were observed with lacosamide.

Example 4 Formalin Model of Persistent Pain in the Rat

Using the same principles of Example 3, an automated system for measuring responses in rats following formalin injection was used to further test the ability of test articles to reduce pain induced by formalin. Following subcutaneous injection of formalin into the hind paw of a rat, flinching behavior (number of events) was measured for sixty minutes post formalin injection using an automated nociception analyzer (ANA Instrument, University of California, San Diego). Automated systems have been validated. See, for example, Yaksh et al. (2001) J. Appl. Physiol. 90:2386-2402.

Briefly, similar to Example 3, a test compound is administered via oral gavage (“PO”) or intraperitoneally 30-60 minutes prior to the subcutaneous injection of formalin to a hind paw of a rat. As with Example 3, “Phase 1” and “Phase 2” responses are detectable. Rather than being measured manually, responses are collected via a system specifically designed to measure the characteristic behavior associated with formalin-induced pain.

For each of saline, morphine, (2R) N-benzyl-2-carboxy mPEG₁ amino-3-methoxy propionamide, (2R) N-benzyl-2-carboxy mPEG₃ amino-3-methoxy propionamide, (2R) N-benzyl-2-carboxy mPEG₅ amino-3-methoxy propionamide, (2R) N-benzyl-2-carboxy mPEG₇ amino-3-methoxy propionamide, FIG. 2 lists the cumulative number of flinches for each of Phase 1 and Phase 2. In this model, tested oligomer-containing articles at a single dose of 100 mg/kg intraperitoneally did not significantly suppress the Phase I or Phase II behaviors induced by formalin. 

What is claimed is:
 1. A compound selected from the group consisting of (2R) N-benzyl-2-carboxy mPEG₁ amino-3-methoxy propionamide, (2R) N-benzyl-2-carboxy mPEG₂ amino-3-methoxy propionamide, (2R) N-benzyl-2-carboxy mPEG₃ amino-3-methoxy propionamide, (2R) N-benzyl-2-carboxy mPEG₄ amino-3-methoxy propionamide, (2R) N-benzyl-2-carboxy mPEG₅ amino-3-methoxy propionamide, (2R) N-benzyl-2-carboxy mPEG₆ amino-3-methoxy propionamide, (2R) N-benzyl-2-carboxy mPEG₇ amino-3-methoxy propionamide, (2R) N-benzyl-2-carboxy mPEG₈ amino-3-methoxy propionamide, (2R) N-benzyl-2-carboxy mPEG₉ amino-3-methoxy propionamide, and pharmaceutically acceptable salts of each of the foregoing.
 2. A compound comprising a 3-alkoxypropionamide residue covalently attached via a linkage to a water-soluble, non-peptidic oligomer, and pharmaceutically acceptable salts thereof.
 3. The compound of claim 2, encompassed within the formula:

wherein: Ar is aryl, optionally substituted with halo; R¹ is lower alkyl; the dotted line (“---”) represents a covalent bond, optionally oriented to provide the R enantiomer; X¹ is a spacer moiety; and POLY¹ is a water-soluble, non-peptidic oligomer, and pharmaceutically acceptable salts thereof.
 4. The compound of claim 2, encompassed within the formula:

wherein: Ar is aryl, optionally substituted with halo; R¹ is lower alkyl; X¹ is a spacer moiety; and POLY¹ is a water-soluble, non-peptidic oligomer, and pharmaceutically acceptable salts thereof.
 5. The compound of claim 2, encompassed within the formula:

wherein: Ar is aryl, optionally substituted with halo; R¹ is lower alkyl; X¹ is a spacer moiety; and POLY¹ is a water-soluble, non-peptidic oligomer, and pharmaceutically acceptable salts thereof.
 6. The compound of claim 2, wherein the 3-alkoxypropionamide residue is a residue of a 3-alkoxypropionamide encompassed within the formula:

wherein: Ar is aryl, optionally substituted with halo; and R¹ is lower alkyl, and pharmaceutically acceptable salts thereof.
 7. The compound of claim 2, wherein the 3-alkoxypropionamide residue is a residue of a 3-alkoxypropionamide selected from the group consisting of (R)—N-benzyl-2-acetamido-3-methoxy propionamide, (R)—N-benzyl-2-acetamido-3-ethoxy propionamide, (R)—N-(3-fluorobenzyl)-2-acetamido-3-methoxy propionamide, and (R)—N-(4-fluorobenzyl)-2-acetamido-3-methoxy propionamide.
 8. The compound of claim 7, wherein the 3-alkoxypropionamide residue is a residue of (R)—N-benzyl-2-acetamido-3-methoxy propionamide.
 9. The compound of any one of claims 2-8, wherein the water-soluble, non-peptidic oligomer is a poly(alkylene oxide).
 10. The compound of claim 9, wherein the poly(alkylene oxide) is a poly(ethylene oxide).
 11. The compound of any one claims 2-10, wherein the water-soluble, non-peptidic oligomer has from about 1 to about 30 monomers.
 12. The compound of claim 11, wherein the water-soluble, non-peptidic oligomer has from about 1 to about 10 monomers.
 13. The compound of claim 9, wherein the poly(alkylene oxide) includes an alkoxy or hydroxy end-capping moiety.
 14. The compound of any one of claims 2-13, wherein a single water-soluble, non-peptidic oligomer is covalently attached to the pyrrolidine residue.
 15. The compound of any one of claims 2-13, wherein two water-soluble, non-peptidic oligomers are covalently attached to the pyrrolidine residue.
 16. The compound of any one of claims 2-15, wherein the linkage is a stable linkage.
 17. The compound of any one of claims 2-15, wherein the linkage is a degradable linkage.
 18. A composition comprising a compound encompassed within claim 1 or 2, and optionally, a pharmaceutically acceptable excipient.
 19. A composition of matter comprising a compound encompassed within claim 1 or 2, wherein the compound is present in a dosage form.
 20. A method of making a conjugate, the method comprising covalently attaching a water-soluble, non-peptidic oligomer to a 3-alkoxypropionamide moiety.
 21. A method comprising administering to a mammal a compound encompassed within claim 1 or
 2. 